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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
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To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

28096 results found.

  1. GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A
  2. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  3. GRB 251117A: Swift-XRT observations
  4. EP251118A / GRB 251118C : MASTER optical counterpart observations
  5. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  6. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  7. EP251118a: VLT near-infrared observation
  8. GRB 251116D: SVOM/GRM observation of a long GRB
  9. GRB 251119A: SVOM detection of a possible burst
  10. EP251118a: Global MASTER-Net observations report
  11. LAT GRB251118.86: Global MASTER-Net observations report
  12. EP251118a: NOT candidate optical counterpart
  13. EP251118a: Einstein Probe detected of a fast X-ray transient
  14. Fermi GRB 251118B: Global MASTER-Net observations report
  15. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  16. GRB 251118A: BALROG localization (Fermi Trigger 785190695 / GRB 251118855)
  17. GRB 251117A: AstroSat CZTI detection
  18. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  19. LIGO/Virgo/KAGRA S251117dq: Updated Sky localization
  20. GRB 251115A: Swift-XRT observations
  21. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  22. GRB 251117A: SVOM/GRM observation of a short burst
  23. LAT GRB251117.51: Global MASTER-Net observations report
  24. LIGO/Virgo/KAGRA S251117dq: Identification of a GW compact binary merger candidate
  25. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  26. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  27. GRB 251116C: Swift-XRT observations
  28. LIGO/Virgo/KAGRA S251116en: Updated Sky localization
  29. GRB 251116D: Glowbug gamma-ray detection
  30. EP251023a: Assy AZT-20 optical observations
  31. EP251023a: UAFO and AbAO optical observations
  32. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  33. GRB 251116C: SVOM/VT optical upper limit
  34. GRB 251025B: further Mondy optical observations
  35. GRB 251111A: Mondy optical upper limit
  36. GRB 251116B: EP-FXT follow-up observation
  37. LIGO/Virgo/KAGRA S251116en: Identification of a GW compact binary merger candidate
  38. LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory
  39. GRB 251116B: LCO optical upper limits
  40. GRB 251116C: LCO optical upper limits
  41. SVOM GRB251116C: Global MASTER-Net observations report
  42. GRB 251116B: SVOM detection of a burst
  43. IceCube-Cascade 251112A: Upper limits from a search for additional neutrino events in IceCube
  44. LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
  45. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  46. Fermi GRB 251115A: Global MASTER-Net observations report
  47. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 4-Update Localization Volume
  48. LIGO/Virgo/KAGRA S251112cm: DECam GW-MMADS candidates
  49. LIGO/Virgo/KAGRA S251112cm: Updated Sky localization and false alarm rate estimate
  50. GRB 251113A: Glowbug gamma-ray detection
  51. GRB 251112A: Swift-BAT refined analysis
  52. Fermi trigger No 784717756: Global MASTER-Net observations report
  53. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  54. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  55. Fermi GRB 251114A: Global MASTER-Net observations report
  56. LIGO/Virgo/KAGRA S251112cm: FTW observations of galaxies within localization region
  57. Fermi GRB 251113A: Global MASTER-Net observations report
  58. GRB 251113A: BALROG localization (Fermi Trigger 784748255 / GRB 251113734)
  59. GRB 251112A: Swift/UVOT Upper Limits
  60. LIGO/Virgo/KAGRA S251112cm: ATLAS pre-detections of AT2025adgp and AT2025adgq
  61. GRB 251112A: Swift-XRT refined Analysis
  62. GRB 251112B: MAXI/GSC detection
  63. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  64. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  65. GRB 251108B: Glowbug gamma-ray detection
  66. Swift Trigger 1413695: a possible GRB 251112A
  67. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  68. Fermi trigger No 784621743: Global MASTER-Net observations report
  69. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 3-Initial Localization Volume
  70. GRB251111A: 1.3m DFOT optical upper limit
  71. LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate
  72. GRB 251106B: Glowbug gamma-ray detection of a likely short burst
  73. GRB 251111A: Swift-XRT afterglow detection
  74. GRB 251111A: SVOM/VT optical observations with X-band data
  75. SVOM GRB251111.42: Global MASTER-Net observations report
  76. GRB 251111A: Swift-XRT observations
  77. SVOM GRB251111.22: Global MASTER-Net observations report
  78. GRB 251111A: EP-FXT counterpart detection
  79. GRB 251013C: Chandra X-ray observations and jet break detection
  80. GRB 251111A: SVOM/VT optical observations with VHF data
  81. GRB 251111A: LCO optical observation
  82. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  83. GRB 251103B: Swift-BAT refined analysis
  84. GRB 251106A: Swift/UVOT Upper Limits
  85. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  86. LIGO/Virgo/KAGRA S251108fi: One counterpart neutrino candidate from IceCube neutrino searches
  87. IceCube-Cascade 251107A: Upper limits from a search for additional neutrino events in IceCube
  88. LIGO/Virgo/KAGRA S251108fi: Updated Sky localization
  89. LIGO/Virgo/KAGRA S251108dn: Updated Sky localization
  90. Fermi trigger No 784329591: Global MASTER-Net observations report
  91. LIGO/Virgo/KAGRA S251108fi: Identification of a GW compact binary merger candidate
  92. Fermi trigger No 784279167: Global MASTER-Net observations report
  93. SVOM GRB251108.54: Global MASTER-Net observations report
  94. GRB 251102B: SVOM/GRM observation
  95. LIGO/Virgo/KAGRA S251108dn: Identification of a GW compact binary merger candidate
  96. SVOM GRB251106.83: Global MASTER-Net observations report
  97. LIGO/Virgo/KAGRA S251105aj: Updated Sky localization
  98. LIGO/Virgo/KAGRA S251103f: Updated Sky localization
  99. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  100. GRB 251106A: Swift-XRT afterglow detection

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