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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"

27400 results found.

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

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