Gamma-ray Burst 991014

On October 14, 1999 a GRB (BATSE trigger 7803) was detected by the BeppoSAX GRBM and WFC instruments and localized to 6 arcmin accuracy. A BeppoSAX follow-up observation with the NFI instruments revealed one hitherto unknown X-ray source.

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• IAUC 7281 WFC discovery

• BeppoSAX GRB alert n. 99/27 and GCN notice #417
  On Oct.14, 21:52:34 UT a GRB (GRB991014) was detected simultaneously by the GRBM and WFC of BeppoSAX (also BATSE trigger 7803). Preliminary coordinates from WFC are:

  R.A.(2000)=102.777
  DEC(2000)= 11.594
  

  with an error radius of about 6'.
• GCN notice #419
  The previous GCN circular (#418) incorrectly referenced an NFI error circle; it should have read:
  K. Hurley, on behalf of the Ulysses GRB team, and M. Feroci, on behalf of the BeppoSAX GRB team, report:
  We have obtained a preliminary IPN annulus for GRB991014 (GCN 417). This annulus is centered at RA=162.2315 deg., Decl.=-19.0726 deg. (J2000), and has a radius of 66.1316 +/- 0.0275 deg. (3 sigma). It intersects the BeppoSAX WFC error circle to form an ~36 arcmin.^2 error box whose corners are:

  RA(2000)        Decl.(2000)
  6 h 50 m 47 s  +11 o  31' 53"
  6 h 51 m 08 s  +11 o  41' 38"
  6 h 50 m 59 s  +11 o  29' 58"
  6 h 51 m 21 s  +11 o  40' 32"
  

  A map may be found at ssl.berkeley.edu/ipn3/991014/. Some refinements to this annulus are expected.
• BeppoSAX MAIL n. 99/28
  A BeppoSAX follow-up of GRB991014 started about 13 hr after the burst. A quick look analysis of the first five orbits of the MECS data at SOC shows only one object, previously unknown, inside the error circle of the WFC. Preliminary coordinates are:

  R.A.(2000)  102.763
  DEC(2000)  11.588
  

  The error radius is 2'.
• GCN notice #420
  K. Hurley, on behalf of the Ulysses GRB team, and M. Feroci, on behalf of the BeppoSAX GRB team, report:
  The recently reported NFI error circle for GRB991014 (BeppoSAX MAIL 99/28) is within the IPN annulus for this burst (GCN 419). The error circle is slightly reduced in size by the annulus. The corners of the IPN/NFI error box are:

     RA(2000)          DEC(2000)
  6 h 50 m 55 s    +11 o 35 ' 34 "
  6 h 50 m 57 s    +11 o 36 ' 43 "
  6 h 51 m 06 s    +11 o 33 ' 23 "
  6 h 51 m 11 s    +11 o 35 ' 54 "
  

  This makes it quite likely that the NFI source is indeed the X-ray counterpart to GRB991014. The map at ssl.berkeley.edu/ipn3/991014/ has been updated to show the NFI source position.
• GCN notice #421
  H. S. Park, R. Porrata (LLNL), G. Williams (Clemson Univ.) report on behalf of the LOTIS collaboration:
  The Super-LOTIS telescope (0.6 m reflector; 0.8 deg fov) responded to the BeppoSAX alert (GCN 417) automatically on Oct 15.528 UT (14.8 hours after the GRB: 5:40 AM local time). The original BATSE trigger 7803 came at 2:21 PM local time and another BATSE trigger 7805 occuring the same evening prevented us from covering the GRB991014 location at earlier times. At the time of this trigger, our camera was not running the TEs because of recent replacement of the CCD (Super-LOTIS is in the integration phase at LLNL.) No astronomical filter was used for these imaging.
  We obtained 9 images (40 s integration time each) before dawn. We have visually compared these individual images and the summed image with the Digital Sky Survey. No new source was identified within the BeppoSAX/WFC error box brighter than R = 16.8 +/- 0.3 from the summed image.
  The LOTIS (17.6 x 17.6 deg fov) telescope was also running and covered trigger 7805; so its sky patrol did not obtain early coverage of the GRB991014 location. The Super-LOTIS limit supercedes the LOTIS limit for the BeppoSAX triggered images.
  Further analysis is in progress and associated data will be placed on our web page.
• GCN notice #422
  The U.S. Naval Observatory GRB team (A.A. Henden, F.J. Vrba, B. Canzian, C.B. Luginbuhl, S.E. Levine, H.H. Guetter, J.A. Munn), D.H. Hartmann (Clemson Univ.), M.C. Jennings (IGPP, UCR visitor)
  report a BVRcIc photometry file for the northern half of the WFI error box of GRB 991014. This file can be found at: ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb991014.dat One marginal photometric night with a wide variety of Landolt standards having large color and airmass differences was used. Typical zero point errors are 0.02mag, to be added to the Poisson errors reported in the file. All stars brighter than V=14 are saturated and should be ignored. We intend to observe additional nights in November to further calibrate this field, and will update the file accordingly.
  The team also acquired I-band photometry with the 1.55-m telescope of the NFI error box, and R-band photometry with the 1.0-m telescope of the entire WFI error box, from about 991015 1030 UT until 1230 UT. Due to the Huntsville GRB meeting, this data is being slowly analyzed by a shrunken staff. It is clear again tonight (991016 UT) and additional R-band photometry with the 1.0-m of the NFI error box is scheduled.
• GCN notice #423
  J. Thorstensen (Dartmouth), R. Uglesich, J. Halpern, N. Mirabal (Columbia U.), E. Costa, M. Feroci, L. Piro (IAS/CNR, Rome) report on behalf of the MDM Observatory GRB follow-up team and the BeppoSAX team:
  We imaged the field of GRB 991014 in the R band starting on Oct. 15.38 UT, 11.2 hours after the burst, using the MDM Observatory's 1.3m and 2.4m telescopes. The entire 6' radius error circle from the BeppoSAX WFC (Gandolfi, GCN #417) was covered at the 1.3m, and the entire 2' radius NFI error circle of a possible X-ray afterglow (BeppoSAX MAIL n. 99/28) was covered at the 2.4m. There was no new object brighter than the digitized POSS-II limit in the WFC error circle.
  We reobserved the NFI error circle on the 2.4m on Oct. 16.42 UT. Seeing was 1.1-1.2 arcseconds on both nights, and the 5 sigma limiting magnitude was R = 23.1. No variable object was detected in the NFI error circle. This magnitude limit is referenced to a USNO star at position (J2000) RA 06:51:03.17, Dec +11:36:42.6 which has R = 17.61 +/- 0.02 according to the recent calibration of Henden et al. (GCN #422).
• GCN notice #424
  T. Giblin, R. M. Kippen (UAH/MSFC), and M. Sahi (USRA/MSFC) report on behalf of the BATSE Team:
  On 1999 October 14.911512 UT, BATSE triggered on GRB991014 (trigger # 7803). The burst time history shows a primary emission pulse comprised of several sub-pulses lasting a few seconds followed by a weak and soft pulse. The T90 and T50 measured durations are 4.67 (+/- 0.47) and 1.22 (+/- 0.14) seconds, respectively. Although short, this burst is still classified as a Class I burst in the BATSE GRB Hardness-Duration scatter plot. The burst is soft, with marginal emission above 300 keV and an energy fluence hardness ratio (100-300 keV / 50-100 keV) equal to 1.36 (+/- 0.13). The 50-300 keV peak flux of the burst measured on the 64 ms timescale is 2.58 (+/- 0.26) photons/s/cm^2 and 4.87 (+/- 0.53) ergs/s/cm^2, placing it in the upper 32% of the BATSE peak flux distribution. The fluence (> 25 keV) of the burst is 1.712 (+/- 0.471) x 10^-6 ergs/cm^2, ranking in the top 58% of the fluence distribution. The BATSE location is consistent with the BeppoSAX WFC error circle and IPN annulus. The BATSE light curve will soon be available at: http://www.batse.msfc.nasa.gov/~kippen/batserbr/
• GCN notice #425
  G. B. Taylor (NRAO), D. A. Frail (NRAO), and S. R. Kulkarni (Caltech) report on behalf of a larger collaboration:
  We have imaged the field of GRB 991014, centered on the BeppoSAX NFI source (BeppoSAX mail n 99/28) with the Very Large Array (VLA) at 1.4 GHz and 8.46 GHz beginning on Oct 16.59 UT. No sources are visible within the region bounded by the NFI error circle above a 5-sigma level of 125 microJy (8.46 GHz) and 220 microJy (1.4 GHz). Further observations are planned.
• GCN notice #426
  S. Guziy, A. Shlyapnikov (Astro. Obs. Nikolaev Univ.), R. Hudec (Astro. Inst. Ondrejov) report:
  We obtained 2 images in the R band of the region for GRB991014 (GCN 417). The total integration time is 1200 s (2x600s). These images were started Oct. 15.96, after the 25.2 hours after the burst on the 0.7 m telescope Astro. Obser. of Nikolaev Univer. The limiting magnitude was about 19.2. Comparison with the Digitized Sky Survey does not reveal any new object brighter than about 19.5 in the intersection of the error regions.
• GCN notice #427
  J. in 't Zand and L. Kuiper, Space Research Organization Netherlands, Utrecht; L.A. Antonelli, Osservatorio Astronomico di Roma; A. Coletta, S. Rebecchi, M. Stornelli, M. Capalbi, BeppoSAX Science Operations Center, Telespazio, Rome; and G. Gandolfi, Istituto di Astrofisica Spaziale, CNR, Rome, report:
  GRB 991014 was observed with the Narrow Field Instruments (NFI) on board BeppoSAX from Oct. 15.4 to 16.4 UT (starting 13.0 hrs after the burst trigger time). In the 2-10 keV image of all data from both Medium-Energy Concentrator Spectrometer units 2 and 3, two point sources are apparent within the WFC/IPN combined error box (Tassone et al., IAUC 7281, Hurley et al. GCN 419). Their positions are R.A. = 6h51m03s, Decl. = +11d36'05" (S1) and R.A. = 6h50m59s, Decl. = +11d33'09" (S2, Eq. 2000.0). The error radius for both sources is 1'.5. Neither S1 nor S2 show conclusive evidence of decay, but this is a statistical issue rather than a meaningful statement about the decay index. To search for a decay and possibly identify the afterglow with S1 or S2, another NFI pointing is scheduled for Oct. 24.
• GCN notice #428
  R. Uglesich, J. Halpern (Columbia U.), & J. Thorstensen (Dartmouth) report:
  In addition to the MDM observations reported in GCN #423, we reobserved the entire 6' radius error circle of the BeppoSAX WFC (Gandolfi, GCN #417) with the 1.3m because it is not known if either of the reported NFI X-ray sources (in 't Zand et al. GCN #427) is associated with the GRB. The 1.3m observations were centered on Oct. 15.45 UT and Oct. 16.48 UT, and reach a 5-sigma limiting magnitude of R = 22.6 on the first night, and R = 22.8 on the second night. We used a non-standard, broad R filter which nevertheless calibrates very well with Landolt (1992) standards that we obtained. We find R = 17.64 for the star mentioned in GCN #423, which is consistent with the USNO calibration (R = 17.61 +/- 0.02). Although we have not yet carried out a detailed photometric analysis of the entire WFC circle, careful visual inspection reveals no variable object to a limit of approximately R > 22.6 at 13 hours after the burst. The images from the MDM 2.4 reported in GCN #423 cover the error circles of both of the NFI sources, and our previously reported limit of R > 23.1 at 11.2 hours still applies.
  We also note that Galactic extinction in this direction is estimated to be E(B-V) = 0.202 from IRAS dust maps (Schlegel et al. 1998), so A_R is a modest 0.54 magnitudes.
  A CCD image of the field of the NFI sources is posted at http://www.astro.bio2.edu/grb/
• GCN notice #429
  J. in 't Zand, Space Research Organization Netherlands (SRON), Utrecht; L.A. Antonelli, Osservatorio Astronomico di Roma; L. Kuiper, SRON; S. Rebecchi, M. Stornelli, D. Ricci, BeppoSAX Science Operations Center, Telespazio, Rome; and G. Gandolfi, Istituto di Astrofisica Spaziale, CNR, Rome, update the information given in GCN Circ. 427.:
  GRB 991014 was observed with the Narrow Field Instruments on board BeppoSAX on two occasions: Oct. 15.4-16.4 UT (0.5-1.5 d after the burst) and Oct. 24.8-25.9 (9.9-11.0 d after the burst). In the 2-10 keV images from both Medium-Energy Concentrator Spectrometer units 2 and 3, two sources only 3' apart are within the combined WFC/IPN error regions of the burst (IAUC 7281, GCN 419). Their positions are R.A. = 6h51m03s, Decl. = +11d36'05" (SAX J0651.0+1136 = S1 in GCN 427; Eq. 2000.0; error radius 1.5') and R.A. = 6h50m57s, Decl. = +11d33'13" (SAX J0651.0+1133 = S2 in GCN 427; error radius 1'). The first source is not detected in the second observation. The 3 sigma upper limit translates to a decay by at least a factor of 2.2. The second source did not change significantly, the intensity change is 10+/-20%. Therefore, we identify SAX J0651.0+1136 as the X-ray afterglow of GRB 991014.