Gamma-ray Burst 220412A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Apr 22 06:37:44 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1102281,   Seg_Num: 0
GRB_RA:          123.968d {+08h 15m 52s} (J2000),
                 124.313d {+08h 17m 15s} (current),
                 123.191d {+08h 12m 46s} (1950)
GRB_DEC:         +30.322d {+30d 19' 19"} (J2000),
                 +30.252d {+30d 15' 09"} (current),
                 +30.476d {+30d 28' 34"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       21154 [cnts]    Image_Peak=407 [image_cnts]
TRIGGER_DUR:     8.192 [sec] 
TRIGGER_INDEX:   477     E_range: 25-100 keV
BKG_INTEN:       151024 [cnts]
BKG_TIME:        23723.05 SOD {06:35:23.05} UT
BKG_DUR:         64 [sec]
GRB_DATE:        19681 TJD;   102 DOY;   22/04/12
GRB_TIME:        23810.22 SOD {06:36:50.22} UT
GRB_PHI:          29.70 [deg]
GRB_THETA:        16.35 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     10.04 [sigma]
IMAGE_SIGNIF:    7.20 [sigma]
MERIT_PARAMS:     +1  +0  +0  +3  +2  -3  +0  +0 +12  +0 
SUN_POSTN:        20.67d {+01h 22m 40s}   +8.70d {+08d 41' 52"}
SUN_DIST:         97.20 [deg]   Sun_angle= -6.9 [hr] (East of Sun)
MOON_POSTN:      150.07d {+10h 00m 16s}  +17.74d {+17d 44' 34"}
MOON_DIST:        26.55 [deg]
MOON_ILLUM:      78 [%]
GAL_COORDS:      192.03, 30.46 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      119.35, 10.28 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This is a rate trigger.  
COMMENTS:        A point_source was found.  
COMMENTS:        This does not match any source in the on-board catalog.  
COMMENTS:        This does not match any source in the ground catalog.  
COMMENTS:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 205.79,20.64 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Apr 22 06:38:59 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     1102281,   Seg_Num: 0
POINT_RA:        123.961d {+08h 15m 51s} (J2000)
POINT_DEC:       +30.325d {+30d 19' 29"} (J2000)
IMG_START_DATE:  19681 TJD;   102 DOY;   22/04/12
IMG_START_TIME:  23932.93 SOD {06:38:52.93} UT,   122.7 [sec] since BAT Trigger Time
COUNTS:          62    Min_needed= 20
STD_DEV:         35.64   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        1    Max_iter_allowed= 4
ERROR_CODE:      3
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        Standard deviation too large.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Apr 22 06:40:20 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1102281,   Seg_Num: 0
GRB_RA:          123.968d {+08h 15m 52s} (J2000),
                 124.313d {+08h 17m 15s} (current),
                 123.191d {+08h 12m 46s} (1950)
GRB_DEC:         +30.322d {+30d 19' 19"} (J2000),
                 +30.252d {+30d 15' 09"} (current),
                 +30.476d {+30d 28' 34"} (1950)
GRB_DATE:        19681 TJD;   102 DOY;   22/04/12
GRB_TIME:        23810.22 SOD {06:36:50.22} UT
TRIGGER_INDEX:   477
GRB_PHI:          29.70 [deg]
GRB_THETA:        16.35 [deg]
DELTA_TIME:      -76.00 [sec]
TRIGGER_DUR:     8.192 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     10.04 [sigma]
IMAGE_SIGNIF:    7.20 [sigma]
LC_URL:          sw01102281000msb.lc
SUN_POSTN:        20.67d {+01h 22m 40s}   +8.70d {+08d 41' 54"}
SUN_DIST:         97.19 [deg]   Sun_angle= -6.9 [hr] (East of Sun)
MOON_POSTN:      150.09d {+10h 00m 21s}  +17.73d {+17d 44' 05"}
MOON_DIST:        26.57 [deg]
MOON_ILLUM:      78 [%]
GAL_COORDS:      192.03, 30.46 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      119.35, 10.28 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Lightcurve.  
COMMENTS:           
COMMENTS:        The next comments were copied from the BAT_POS Notice:  
COMMENTS:        This is a rate trigger.  
COMMENTS:        A point_source was found.  
COMMENTS:        This does not match any source in the on-board catalog.  
COMMENTS:        This does not match any source in the ground catalog.  
COMMENTS:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 205.79,20.64 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Apr 22 06:41:45 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1102281,   Seg_Num: 0
POINT_RA:        123.961d {+08h 15m 51s} (J2000)
POINT_DEC:       +30.324d {+30d 19' 28"} (J2000)
POINT_ROLL:      284.283d
IMG_START_DATE:  19681 TJD;   102 DOY;   22/04/12
IMG_START_TIME:  23936.82 SOD {06:38:56.82} UT,   126.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.994
N_STARS:         42
X_OFFSET:        425 [pixels]
Y_OFFSET:        586 [pixels]
X_MAX:           1384 [pixels]
Y_MAX:           1545 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    8
SL_URL:          sw01102281000msufc0126.fits
SUN_POSTN:        20.67d {+01h 22m 41s}   +8.70d {+08d 41' 56"}
SUN_DIST:         97.19 [deg]   Sun_angle= -6.9 [hr] (East of Sun)
MOON_POSTN:      150.10d {+10h 00m 24s}  +17.73d {+17d 43' 49"}
MOON_DIST:        26.59 [deg]
MOON_ILLUM:      78 [%]
GAL_COORDS:      192.02, 30.45 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      119.34, 10.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Apr 22 06:41:59 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1102281,   Seg_Num: 0
POINT_RA:        123.961d {+08h 15m 51s} (J2000)
POINT_DEC:       +30.324d {+30d 19' 28"} (J2000)
POINT_ROLL:      284.283d
IMG_START_DATE:  19681 TJD;   102 DOY;   22/04/12
IMG_START_TIME:  23936.82 SOD {06:38:56.82} UT,   126.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.994
N_STARS:         42
X_OFFSET:        425 [pixels]
Y_OFFSET:        586 [pixels]
X_MAX:           1384 [pixels]
Y_MAX:           1545 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    8
SL_URL:          sw01102281000msufc0126.fits
SUN_POSTN:        20.67d {+01h 22m 41s}   +8.70d {+08d 41' 56"}
SUN_DIST:         97.19 [deg]   Sun_angle= -6.9 [hr] (East of Sun)
MOON_POSTN:      150.10d {+10h 00m 24s}  +17.73d {+17d 43' 47"}
MOON_DIST:        26.59 [deg]
MOON_ILLUM:      78 [%]
GAL_COORDS:      192.02, 30.45 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      119.34, 10.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Apr 22 06:44:38 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1102281,   Seg_Num: 0
POINT_RA:        123.961d {+08h 15m 51s} (J2000)
POINT_DEC:       +30.324d {+30d 19' 28"} (J2000)
ROLL:            284.283d
IMG_START_DATE:  19681 TJD;   102 DOY;   22/04/12
IMG_START_TIME:  23936.82 SOD {06:38:56.82} UT,   126.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     671438365
X_OFFSET:        744 [pixels]
Y_OFFSET:        905 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       904
Y_GRB_POS:       1065
BINNING_INDEX:   1
IM_URL:          sw01102281000msuni0155.fits
SUN_POSTN:        20.67d {+01h 22m 41s}   +8.70d {+08d 41' 58"}
SUN_DIST:         97.18 [deg]   Sun_angle= -6.9 [hr] (East of Sun)
MOON_POSTN:      150.12d {+10h 00m 30s}  +17.72d {+17d 43' 17"}
MOON_DIST:        26.62 [deg]
MOON_ILLUM:      78 [%]
GAL_COORDS:      192.02, 30.45 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      119.34, 10.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Apr 22 06:44:44 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1102281,   Seg_Num: 0
POINT_RA:        123.961d {+08h 15m 51s} (J2000)
POINT_DEC:       +30.324d {+30d 19' 28"} (J2000)
ROLL:            284.283d
IMG_START_DATE:  19681 TJD;   102 DOY;   22/04/12
IMG_START_TIME:  23936.82 SOD {06:38:56.82} UT,   126.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     671438365
X_OFFSET:        744 [pixels]
Y_OFFSET:        905 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       904
Y_GRB_POS:       1065
BINNING_INDEX:   1
IM_URL:          sw01102281000msuni0155.fits
SUN_POSTN:        20.67d {+01h 22m 41s}   +8.70d {+08d 41' 58"}
SUN_DIST:         97.18 [deg]   Sun_angle= -6.9 [hr] (East of Sun)
MOON_POSTN:      150.13d {+10h 00m 30s}  +17.72d {+17d 43' 16"}
MOON_DIST:        26.62 [deg]
MOON_ILLUM:      78 [%]
GAL_COORDS:      192.02, 30.45 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      119.34, 10.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN Circular #31880
V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D.Cheryasov, Ya.Kechin (Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias),
D. Buckley (South African Astronomical Observatory),
O.A. Gres, N.M. Budnev (Irkutsk State University, API),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational State University)
MASTER-OAGH robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Mexico (OAGH National Institute for Astrophysics, Optics and Electronics) was pointed to the Swift GRB220412.28 (trigger No 1102281,08h 15m 52.32s , +30d 19m 19.2s, R=0.05) errorbox 37 sec after notice time and 97 sec after trigger time at 2022-04-12 06:38:27 UT, with upper limit up to 14.9 mag. The observations began at zenith distance = 56 deg. The sun altitude is -49.2 deg.
The galactic latitude b = 31 deg., longitude l = 192 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1940522
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

     108 |         MASTER-OAGH |  P- |    20 | 14.8 |        
     155 |         MASTER-OAGH |  P- |    30 | 14.9 |        
     211 |         MASTER-OAGH |  P- |    40 | 14.9 |        
```
The observation and reduction will continue. The message may be cited.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Apr 22 06:47:27 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1102281,   Seg_Num: 0
GRB_RA:          123.9646d {+08h 15m 51.50s} (J2000),
                 124.3100d {+08h 17m 14.41s} (current),
                 123.1879d {+08h 12m 45.09s} (1950)
GRB_DEC:         +30.3431d {+30d 20' 35.1"} (J2000),
                 +30.2735d {+30d 16' 24.6"} (current),
                 +30.4971d {+30d 29' 49.4"} (1950)
GRB_ERROR:       4.5 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  19681 TJD;   102 DOY;   22/04/12
IMG_START_TIME:  24097.00 SOD {06:41:37.00} UT,   286.8 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        20.67d {+01h 22m 42s}   +8.70d {+08d 42' 01"}
SUN_DIST:         97.18 [deg]   Sun_angle= -6.9 [hr] (East of Sun)
MOON_POSTN:      150.15d {+10h 00m 36s}  +17.71d {+17d 42' 46"}
MOON_DIST:        26.64 [deg]
MOON_ILLUM:      78 [%]
GAL_COORDS:      192.00, 30.46 [deg] galactic lon,lat of the burst
ECL_COORDS:      119.34, 10.30 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.58% < P(seren) < 1.1%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Apr 22 06:51:16 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1102281,   Seg_Num: 0
POINT_RA:        123.958d {+08h 15m 50s} (J2000)
POINT_DEC:       +30.324d {+30d 19' 27"} (J2000)
POINT_ROLL:      284.277d
IMG_START_DATE:  19681 TJD;   102 DOY;   22/04/12
IMG_START_TIME:  24094.83 SOD {06:41:34.83} UT,   284.6 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.808
N_STARS:         51
X_OFFSET:        185 [pixels]
Y_OFFSET:        346 [pixels]
X_MAX:           1624 [pixels]
Y_MAX:           1785 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    3
SL_URL:          sw01102281000msufc0284.fits
SUN_POSTN:        20.68d {+01h 22m 42s}   +8.70d {+08d 42' 04"}
SUN_DIST:         97.18 [deg]   Sun_angle= -6.9 [hr] (East of Sun)
MOON_POSTN:      150.18d {+10h 00m 44s}  +17.70d {+17d 42' 04"}
MOON_DIST:        26.67 [deg]
MOON_ILLUM:      78 [%]
GAL_COORDS:      192.02, 30.45 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      119.34, 10.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Apr 22 06:52:23 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1102281,   Seg_Num: 0
POINT_RA:        123.958d {+08h 15m 50s} (J2000)
POINT_DEC:       +30.324d {+30d 19' 27"} (J2000)
ROLL:            284.277d
IMG_START_DATE:  19681 TJD;   102 DOY;   22/04/12
IMG_START_TIME:  24094.83 SOD {06:41:34.83} UT,   284.6 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     671438523
X_OFFSET:        744 [pixels]
Y_OFFSET:        905 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       904
Y_GRB_POS:       1065
BINNING_INDEX:   1
IM_URL:          sw01102281000msuni0313.fits
SUN_POSTN:        20.68d {+01h 22m 42s}   +8.70d {+08d 42' 05"}
SUN_DIST:         97.18 [deg]   Sun_angle= -6.9 [hr] (East of Sun)
MOON_POSTN:      150.19d {+10h 00m 46s}  +17.70d {+17d 41' 51"}
MOON_DIST:        26.68 [deg]
MOON_ILLUM:      78 [%]
GAL_COORDS:      192.02, 30.45 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      119.34, 10.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Apr 22 06:51:31 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1102281,   Seg_Num: 0
POINT_RA:        123.958d {+08h 15m 50s} (J2000)
POINT_DEC:       +30.324d {+30d 19' 27"} (J2000)
POINT_ROLL:      284.277d
IMG_START_DATE:  19681 TJD;   102 DOY;   22/04/12
IMG_START_TIME:  24094.83 SOD {06:41:34.83} UT,   284.6 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.808
N_STARS:         51
X_OFFSET:        185 [pixels]
Y_OFFSET:        346 [pixels]
X_MAX:           1624 [pixels]
Y_MAX:           1785 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    3
SL_URL:          sw01102281000msufc0284.fits
SUN_POSTN:        20.68d {+01h 22m 42s}   +8.70d {+08d 42' 05"}
SUN_DIST:         97.18 [deg]   Sun_angle= -6.9 [hr] (East of Sun)
MOON_POSTN:      150.18d {+10h 00m 44s}  +17.70d {+17d 42' 01"}
MOON_DIST:        26.68 [deg]
MOON_ILLUM:      78 [%]
GAL_COORDS:      192.02, 30.45 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      119.34, 10.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Apr 22 06:52:36 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1102281,   Seg_Num: 0
POINT_RA:        123.958d {+08h 15m 50s} (J2000)
POINT_DEC:       +30.324d {+30d 19' 27"} (J2000)
ROLL:            284.277d
IMG_START_DATE:  19681 TJD;   102 DOY;   22/04/12
IMG_START_TIME:  24094.83 SOD {06:41:34.83} UT,   284.6 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     671438523
X_OFFSET:        744 [pixels]
Y_OFFSET:        905 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       904
Y_GRB_POS:       1065
BINNING_INDEX:   1
IM_URL:          sw01102281000msuni0313.fits
SUN_POSTN:        20.68d {+01h 22m 42s}   +8.70d {+08d 42' 06"}
SUN_DIST:         97.18 [deg]   Sun_angle= -6.9 [hr] (East of Sun)
MOON_POSTN:      150.19d {+10h 00m 46s}  +17.70d {+17d 41' 49"}
MOON_DIST:        26.69 [deg]
MOON_ILLUM:      78 [%]
GAL_COORDS:      192.02, 30.45 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      119.34, 10.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN Circular #31881
N. J. Klingler (GSFC/UMBC/CRESSTII), J.D. Gropp (PSU), K. L. Page (U Leicester), D. M. Palmer (LANL), T. M. Parsotan (GSFC/UMBC/CRESSTII), B. Sbarufatti (PSU) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team:
At 06:36:50 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 220412A (trigger=1102281). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 123.968, +30.322 which is
```
   RA(J2000) = 08h 15m 52s
   Dec(J2000) = +30d 19' 19"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 20 sec. The peak count rate was ~900 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 06:38:52.9 UT, 122.7 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 123.96470, 30.34319 which is equivalent to:
```
   RA(J2000)  = 08h 15m 51.53s
   Dec(J2000) = +30d 20' 35.5"
```
with an uncertainty of 4.5 arcseconds (radius, 90% containment). This location is 76 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at https://www.swift.ac.uk/sper. We cannot determine whether the source is fading at the present time. No spectrum from the promptly downlinked event data is yet available to determine the column density.
UVOT took a finding chart exposure of 150 seconds with the White filter starting 126 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.037.
Burst Advocate for this burst is N. J. Klingler (noelklin AT umbc.edu). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/)

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Apr 22 06:59:03 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1102281,   Seg_Num: 0
POINT_RA:        123.959d {+08h 15m 50s} (J2000)
POINT_DEC:       +30.323d {+30d 19' 25"} (J2000)
POINT_ROLL:      284.280d
IMG_START_DATE:  19681 TJD;   102 DOY;   22/04/12
IMG_START_TIME:  24673.43 SOD {06:51:13.43} UT,   863.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.831
N_STARS:         88
X_OFFSET:        185 [pixels]
Y_OFFSET:        346 [pixels]
X_MAX:           1624 [pixels]
Y_MAX:           1785 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    7
SL_URL:          sw01102281000msufc0863.fits
SUN_POSTN:        20.68d {+01h 22m 43s}   +8.70d {+08d 42' 11"}
SUN_DIST:         97.17 [deg]   Sun_angle= -6.9 [hr] (East of Sun)
MOON_POSTN:      150.25d {+10h 01m 00s}  +17.68d {+17d 40' 37"}
MOON_DIST:        26.74 [deg]
MOON_ILLUM:      78 [%]
GAL_COORDS:      192.02, 30.45 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      119.34, 10.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Apr 22 06:59:13 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1102281,   Seg_Num: 0
POINT_RA:        123.959d {+08h 15m 50s} (J2000)
POINT_DEC:       +30.323d {+30d 19' 25"} (J2000)
POINT_ROLL:      284.280d
IMG_START_DATE:  19681 TJD;   102 DOY;   22/04/12
IMG_START_TIME:  24673.43 SOD {06:51:13.43} UT,   863.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.831
N_STARS:         88
X_OFFSET:        185 [pixels]
Y_OFFSET:        346 [pixels]
X_MAX:           1624 [pixels]
Y_MAX:           1785 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    7
SL_URL:          sw01102281000msufc0863.fits
SUN_POSTN:        20.68d {+01h 22m 43s}   +8.70d {+08d 42' 12"}
SUN_DIST:         97.17 [deg]   Sun_angle= -6.9 [hr] (East of Sun)
MOON_POSTN:      150.25d {+10h 01m 00s}  +17.68d {+17d 40' 35"}
MOON_DIST:        26.74 [deg]
MOON_ILLUM:      78 [%]
GAL_COORDS:      192.02, 30.45 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      119.34, 10.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Apr 22 07:00:41 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1102281,   Seg_Num: 0
POINT_RA:        123.959d {+08h 15m 50s} (J2000)
POINT_DEC:       +30.323d {+30d 19' 25"} (J2000)
ROLL:            284.280d
IMG_START_DATE:  19681 TJD;   102 DOY;   22/04/12
IMG_START_TIME:  24673.43 SOD {06:51:13.43} UT,   863.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     671439102
X_OFFSET:        744 [pixels]
Y_OFFSET:        905 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       904
Y_GRB_POS:       1065
BINNING_INDEX:   1
IM_URL:          sw01102281000msuni0892.fits
SUN_POSTN:        20.68d {+01h 22m 44s}   +8.70d {+08d 42' 13"}
SUN_DIST:         97.17 [deg]   Sun_angle= -6.9 [hr] (East of Sun)
MOON_POSTN:      150.26d {+10h 01m 03s}  +17.67d {+17d 40' 19"}
MOON_DIST:        26.75 [deg]
MOON_ILLUM:      78 [%]
GAL_COORDS:      192.02, 30.45 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      119.34, 10.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Apr 22 07:00:51 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1102281,   Seg_Num: 0
POINT_RA:        123.959d {+08h 15m 50s} (J2000)
POINT_DEC:       +30.323d {+30d 19' 25"} (J2000)
ROLL:            284.280d
IMG_START_DATE:  19681 TJD;   102 DOY;   22/04/12
IMG_START_TIME:  24673.43 SOD {06:51:13.43} UT,   863.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     671439102
X_OFFSET:        744 [pixels]
Y_OFFSET:        905 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       904
Y_GRB_POS:       1065
BINNING_INDEX:   1
IM_URL:          sw01102281000msuni0892.fits
SUN_POSTN:        20.68d {+01h 22m 44s}   +8.70d {+08d 42' 13"}
SUN_DIST:         97.17 [deg]   Sun_angle= -6.9 [hr] (East of Sun)
MOON_POSTN:      150.26d {+10h 01m 04s}  +17.67d {+17d 40' 17"}
MOON_DIST:        26.76 [deg]
MOON_ILLUM:      78 [%]
GAL_COORDS:      192.02, 30.45 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      119.34, 10.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Apr 22 07:13:51 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     1102281,   Seg_Num: 0
GRB_RA:          123.9655d {+08h 15m 51.72s} (J2000),
                 124.3109d {+08h 17m 14.62s} (current),
                 123.1888d {+08h 12m 45.30s} (1950)
GRB_DEC:         +30.3423d {+30d 20' 32.2"} (J2000),
                 +30.2727d {+30d 16' 21.7"} (current),
                 +30.4963d {+30d 29' 46.5"} (1950)
GRB_ERROR:       3.8 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  19681 TJD;   102 DOY;   22/04/12
IMG_START_TIME:  24097.00 SOD {06:41:37.00} UT,   286.8 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        20.69d {+01h 22m 46s}   +8.71d {+08d 42' 25"}
SUN_DIST:         97.17 [deg]   Sun_angle= -6.9 [hr] (East of Sun)
MOON_POSTN:      150.38d {+10h 01m 30s}  +17.63d {+17d 37' 52"}
MOON_DIST:        26.87 [deg]
MOON_ILLUM:      78 [%]
GAL_COORDS:      192.00, 30.46 [deg] galactic lon,lat of the burst
ECL_COORDS:      119.34, 10.30 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        This is an Update Notice -- the RA,Dec values herein supersede the previous XRT_POS Notice.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.58% < P(seren) < 1.1%.

GCN Circular #31882
Alan M. Watson (UNAM), Eleonora Troja (UTV), Nat Butler (ASU), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Enrico Ramirez-Ruiz (UCSC), Jes�s Gonz�lez (UNAM), Carlos Rom�n-Z��iga (UNAM), Harvey Moseley (GSFC), Rosa L. Becerra (UNAM), Simone Dichiara (PSU), and Oc�lotl L�pez (UNAM) report:
We observed the field of GRB 220412A (Klingler et al. GCN 31881) with the Reionization and Transients Infrared Camera (RATIR) on the 1.5m Harold Johnson Telescope at the Observatorio Astron�mico Nacional on Sierra San Pedro M�rtir from 2022/04 12.28 to 2022/04 12.29 UTC (0.1 to 0.5 hours after the BAT trigger), obtaining a total of 0.21 hours exposure in the r and i bands and 0.08 hours exposure in the Z, Y, J, and H bands.
We detect a bright, uncataloged source at RA = 123.967275 and declination = 30.342693 degrees (J2000), about 5.5 arcsec to the east of the current Swift XRT SPER position. In comparison with the SDSS DR9 and 2MASS catalogs, we obtain the following magnitudes:
```
   r = 19.41 +/- 0.12
   i = 19.26 +/- 0.10
   Y = 19.11 +/- 0.23
```
These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB.
Despite being slightly outside the current XRT error region, we suggest that this source is likely to be the afterglow. Observations are continuing.
We thank the staff of the Observatorio Astron�mico Nacional in San Pedro M�rtir.
GCN Circular #31885
A. Breeveld (UCL-MSSL) and N. Klingler (GSFC/UMBC/CRESSTII) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 220412A 127 s after the BAT trigger (Klingler et al., GCN Circ. 31881). No optical afterglow consistent with the RATIR position (Watson et al., GCN Circ. 31882) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposures and subsequent exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           127          276          147         >20.5
u_FC               285          479          191         >19.6
white              566          758           34         >19.7
b                  542          734           34         >18.97
v                  616         1059           53         >18.18
uvw1               665          857           34         >18.25
uvw2               592         1039           58         >18.64
uvm2               813          833           20         >17.37
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.0373 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #31887
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team.
Using 1814 s of XRT Photon Counting mode data and 2 UVOT images for GRB 220412A, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 123.96809, +30.34259 which is equivalent to:
```
RA (J2000): 08h 15m 52.34s
Dec (J2000): +30d 20' 33.3"
```
with an uncertainty of 3.7 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the Swift-XRT team.
GCN Circular #31888
A. D'Ai (INAF-IASFPA), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), A. Melandri (INAF-OAB), T. Sbarrato (INAF-OAB) and N.J. Klingler report on behalf of the Swift-XRT team:
We have analysed 8.6 ks of XRT data for GRB 220412A (Klingler et al. GCN Circ. 31881), from 106 s to 68.7 ks after the BAT trigger. The data comprise 158 s in Windowed Timing (WT) mode (the first 9 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN Circ. 31887).
The light curve can be modelled with an initial power-law decay with an index of alpha=2.10 (+0.08, -0.07), followed by a break at T+4017 s to an alpha of 0.0 (+0.0, -1.1).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.02 (+0.18, -0.09). The best-fitting absorption column is consistent with the Galactic value of 3.7 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.68 (+0.22, -0.18) and a best-fitting absorption column of 5.7 (+5.9, -2.0) x 10^20 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.9 x 10^-11 (4.3 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     5.7 (+5.9, -2.0) x 10^20 cm^-2
Galactic foreground: 3.7 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.68 (+0.22, -0.18)
```
If the light curve continues to decay with a power-law decay index of 0.0, the count rate at T+24 hours will be 0.011 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.4 x 10^-13 (4.7 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01102281.
This circular is an official product of the Swift-XRT team.
GCN Circular #31890
K.L. Page (U. Leicester) reports on behalf of the Swift-XRT team:
In GCN 31888, the fit to the XRT light curve was stated incorrectly. There correct details are as follows:
The light curve can be modelled with an initial power-law decay with an index of alpha=2.10 (+0.08, -0.07), followed by a break at T+1330 s to an alpha of 0.98 (+0.13, -0.28).
If the light curve continues to decay with a power-law decay index of 0.98, the count rate at T+24 hours will be 1.9e-03 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.4 x 10^-14 (8.1 x 10^-14) erg cm^-2 s^-1.
The remaining details in GCN 31888 were correct. We apologise for any inconveniece.
This circular is an official product of the Swift-XRT team.
GCN Circular #31891
K. L. Murata, M. Niwano, Y. Imai, N. Ito, Y. Takamatsu, S. Sato, R. Hosokawa, M. Sasada, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration:
We observed the field of GRB 220412A (Klingler et al. GCN Circular #31881, Watson et al. GCN Circular #31882, Breeveld and Klingler et al. GCN Circular #31885, Evans et al. GCN Circular #31887, D'Ai et al. GCN Circular #31888) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope Akeno. The observation with a series of 60 sec exposures started at 2022-04-12 10:10:00 UT (214 minutes after the Swift/BAT trigger). We stacked the images with good conditions. We did not detect any uncatalogued sources within the enhanced XRT error region (Evans et al. GCN Circular #31887). We obtained the 5-sigma limits of the stacked images as follows.
```
T0+[min] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
214 2022-04-12 10:53:37 3960 g'>19.0, Rc>19.3, Ic>18.8
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
```
We used the PS1 catalog for flux calibration. The magnitudes are expressed in the AB system. The images were processed in real-time through the MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ, Vol.73, Issue 1, Pages 4-24; https://github.com/MNiwano/Eclaire).
GCN Circular #31898
Alan M. Watson (UNAM), Nat Butler (ASU), Eleonora Troja (UTV), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Enrico Ramirez-Ruiz (UCSC), Jes�s Gonz�lez (UNAM), Carlos Rom�n-Z��iga (UNAM), Harvey Moseley (GSFC), Rosa L. Becerra (UNAM), Simone Dichiara (PSU), and Oc�lotl L�pez (UNAM) report:
We observed the field of GRB 220412A (Klingler et al. GCN 31881) with the Reionization and Transients Infrared Camera (RATIR) on the 1.5m Harold Johnson Telescope at the Observatorio Astron�mico Nacional on Sierra San Pedro M�rtir from 2022-04-12 06:39 to 06:56 UTC (0.04 to 0.33 hours after the trigger) and 2022-04-13 03:16 to 04:38 UTC (20.65 to 22.00 hours after the trigger) obtaining totals of 0.21 and 1.07 hours of exposure in the i band.
In comparison with the SDSS DR9 catalog, the afterglow candidate reported by Watson et al. (GCN Circ. 31882) has faded from i = 19.27 +/- 0.10 to i = 20.64 +/- 0.08. This photometry for the first night supersedes the preliminary photometry reported by Watson et al.
We note that the optical light curve does not seem to show the same steep decline as the XRT light curve reported by the UKSSDC. From 0.33 to 21 hours, the XRT light curve falls by a factor of about 50, whereas our photometry only falls by a factor of about 3.5.
We have checked the SDSS DR9 i image, and there is no apparent host galaxy present at the position of the afterglow bright enough to explain the apparent slow decline.
Further observations are planned.
We thank the staff of the Observatorio Astron�mico Nacional in San Pedro M�rtir.
GCN Circular #31899
T. Parsotan (GSFC/UMBC), S. D. Barthelmy (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 220412A (trigger #1102281)
(Klingler et al. GCN Circ. 31881). The BAT ground-calculated position is
RA, Dec = 123.975, 30.336 deg which is
RA(J2000) = 08h 15m 54.0s
Dec(J2000) = +30d 20' 08.5"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 92%.
The BAT light curve showed a complex
structure with a duration of about 20 sec. The peak count rate
was ~900 counts/sec (15-350 keV), at ~1 sec after the trigger.
T90 (15-350 keV) is 41.66 +- 7.00 sec (estimated error including systematics).

The time-averaged spectrum from T-11.07 to T+38.00 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.53 +- 0.21. The fluence in the 15-150 keV band is 5.9 +- 0.9 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T+6.88 sec in the 15-150 keV band
is 0.5 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence
level.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1102281/BA/
GCN Circular #31901
Y.-D. Hu, E. Fernandez-Garcia, A. J. Castro-Tirado, T.-R. Sun, M. D. Caballero-Garcia, R. Sanchez-Ramirez (IAA-CSIC), D. Hiriart and W. H. Lee (UNAM), C. Perez del Pulgar, A. Castellon, I. Carrasco, A. Reina (Univ. de Malaga), I. H. Park (SKKU) and F. Rendon (IAA-CSIC and INTA-CEDEA) on behalf of a larger collaboration, report:
Following the detection of GRB 220412A by Swift (Klingler et al., GCNC 31881), the 0.3m BOOTES-1B robotic telescope in Mazagon (Huelva), southern Spain, automatically responded to this burst on Apr 12 at 22:41 UT (i.e. ~16.1 hours after trigger). In the co-added frame (52 x 60 s, clear filter), no source is detected within the enhanced XRT position (Evans et al., GCNC 31887) down to 19.2 mag.
Later on, the 60cm BOOTES-5/JGT robotic telescope at Observatorio Astronomico Nacional in San Pedro Martir (Mexico) automatically responded to this burst on Apr 13 at 03:33 UT (i.e. ~ 21 hrs after trigger). In the co-added image (45 x 60 s, clear filter), no optical afterglow is detected within the enhanced XRT position (Evans et al., GCNC 31887) down to 20.3 mag.
Although the candidate reported by RATIR (Watson et al. GCNC 31882, GCNC 31898) is not detected, those non-detections are consistent with the reports from Swift/UVOT (Klingler et al., GCNC 31881, Breeveld et al. GCNC 31885), MITSuME (Murata et al. GCNC 31891) and MASTER-Net (Lipunov et al., GCNC 31880).
We thank the staff at INTA-CEDEA and San Pedro Martir Observatory for their excellent support.
GCN Circular #31902
Alan M. Watson (UNAM), Nat Butler (ASU), Eleonora Troja (UTV), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Enrico Ramirez-Ruiz (UCSC), Jes�s Gonz�lez (UNAM), Carlos Rom�n-Z��iga (UNAM), Harvey Moseley (GSFC), Rosa L. Becerra (UNAM), Simone Dichiara (PSU), and Oc�lotl L�pez (UNAM) report:
We observed the field of GRB 220412A (Klingler et al. GCN 31881) with the Reionization and Transients Infrared Camera (RATIR) on the 1.5m Harold Johnson Telescope at the Observatorio Astron�mico Nacional on Sierra San Pedro M�rtir from 2022-04-14 03:28 to 07:30 UTC (44.9 to 48.9 hours after the trigger) obtaining 2.31 hours of exposure in the i band.
In comparison with the SDSS DR9 catalog, the afterglow candidate reported by Watson et al. (GCN Circ. 31882, 31898) is detected at i = 21.51 +/- 0.10.
We note that the optical light curve appears to have steepened. The temporal index between our observations at 21 hours (Watson et al., GCN Circ 31898) and 47 hours is close to -1.0.
Further observations are continuing.
We thank the staff of the Observatorio Astron�mico Nacional in San Pedro M�rtir.
GCN Circular #31903
GRB 220412A: GRANDMA observations
Content:
S. Beradze (AbAO), U. Bhardwaj (GRAPPA), T. Culino (ESILV), P. Hello (IJCLAB), M. Masek (FZU), G. Raaijmakers (GRAPPA), Y. Rajabov (UBAI), T. Sadibekova (AIM/CEA-UPS), F. Z. Guo (THU), X. F. Wang (THU/BJP), Y. Zhu (NAOC), J. Zhang (NAOC), D. A. Kann (HETH/IAA-CSIC), K. Noysena (NARIT), A. Kaouech (OUCA/KNC) C. Rinner (OUCA), Z. Benkhaldoun (OUCA), S. Antier (OCA/Artemis), P. A. Duverne (IJCLAB), M. Freeberg (KNC), R. Hainich (UP), F. Runger (UP), S. Karpov (FZU), A. Simon (Kyiv Univ), A. Baransky (Kyiv Univ) and V. Godunova (IC ICAMER) report on behalf of GRANDMA collaboration:
The GRANDMA telescope network responded to the alert of GRB 220412A (N. J. Klingler et al. GCNC 31881, P.A. Evans et al. GCN 31887, A. D'Ai et al. GCN 31888, K.L. Page et al GCN 31890). The first observations started ** h after the SWIFT BAT trigger time.
We did not detect the optical afterglow within the first 24 h. Upper limits are given in the AB system, at 3-sigma.
```
T-T0(hr)| MJD��� | Observatory� | Exposure| Filter | Upp. Lim. (AB)
_____________________________________________________
05.55 |59681.50689|Xinglong-2.16m|12*300s��� |� R���� |�� 19.5
14.02 |59681.86193|OST/CDK20���� |18*180s��� |� R���� |�� 17.8
14.07 |59681.85977|OST/CDK20���� |17*180s��� |� I���� |�� 17.0
17.36 |59681.99881|KNC-HAO������ |5*180s���� |� L��� � |�� 17.3
21.18 |59682.15807|TRT-SRO������ |10*60s���� |� V ��� � |�� 18.1
21.35 |59682.16537|TRT-SRO������ |10*60s���� |� R ��� � |�� 17.7
21.53 |59682.17271|TRT-SRO������ |10*60s���� |� I ��� � |�� 17.1
21.95 |59682.19014|KNC-T24������ |3300s����� |� I ��� � |�� 18.1
```
The observations were contaminated by the moon.
These upper limits are consistent with previous reports of detections by RATIR (Alan M. Watson et al., GCN 31882 & GCN 31902) and the upper limits provided by UVOT (A. Breeveld and N. Klingler, GCN 31885), MITSuME Akeno (K. L. Murata et al., GCN 31891).
The Xinglong-2.16m and TRT-SRO data have been calibrated using nearby stars from the Pan-STARRS catalog. The measurements for� Xinglong-2.16m provided by the STDPipe pipeline (Karpov 2022). The OST data have been using CDK filter and calibrated with USNO-B1.0 Catalog (Monet+ 2003). The KNC-T24 and KNC-HAO images have been calibrated using field stars from the PanSTARRS-DR1 catalog, measured with the MUPHOTEN pipeline (Duverne et al. 2021).
GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is the citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/).
GCN Circular #32326
K. Noonan (UVI), P. Gokuldass (Florida Institute of Technology), N. Orange (OrangeWave Innovative Science, LLC), K. Smith (UVI), D. Morris (UVI) report:
We observed the field of GRB220412A (N. J. Klingler et al., GCN 31881) with the 0.5m Virgin Island Robotic Telescope (VIRT) at the University of the Virgin Islands' Etelman Observatory on 04-13-2022 starting at 00:11:58.73 UT (T+17.30 hrs). We performed a series of exposures in the R filter with a total exposure of 4000 s. The weather conditions were partly cloudy during the hours of observation with an average airmass of 1.25.
We find no new source within the enhanced XRT position error circle (P. A. Evans et al., 31887) and report the following 5-sigma upper limit:
T_mid ||Exposure ||Filter ||Limit
T+ 18.2 hrs ||4000s ||R ||>20.8
The limit is estimated from comparison to nearby USNO B1 stars and is not corrected for Galactic extinction. The VIRT is still in the commissioning phase.
We acknowledge financial support from NASA MUREP MIRO award 80NSSC21M0001, NASA EPSCoR award 80NSSC19M0060, and NSF EiR award 1901296.This message can be cited.

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Jochen Greiner, last update: 05-Jul-2022 [Disclaimer]