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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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').
Advanced Search

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.

Advanced Search Examples (click to copy):

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

45700 results found.

  1. GRB 250706B/C: VLT/X-shooter redshift z = 0.942
  2. IceCube-250706A: EP-FXT follow-up observations
  3. Fermi-LAT Gamma-ray Observations of IceCube-250706A
  4. GRB 250706B/C: Fermi-LAT detection
  5. IceCube-250706A: Global MASTER-Net observations report
  6. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  7. EP250702a/GRB250702 B,D,E: GRANDMA Upper Limit
  8. GRB 250706B: Swift/UVOT Detection
  9. EP250702a/ GRB 250702B: NuSTAR X-ray Observations
  10. GRB 250706C: Konus-Wind detection of a very bright GRB ~1200 s before GRB 250706B
  11. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  12. GRB 250702F: GRANDMA observations
  13. GRB 250706A: Swift-XRT refined Analysis
  14. GRB 250706B: refined SVOM/MXT data analysis
  15. GRB 250706A: Swift/UVOT Upper Limits
  16. GRB 250706B: REM optical observations
  17. GRB 250706A: REM optical/NIR observations
  18. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  19. IceCube-250416A: DDOTI Optical Upper Limit
  20. IceCube-250706A: COLIBRÍ optical upper limits
  21. Swift GRB 250706A: Global MASTER-Net observations report
  22. GRB 250706A: JinShan optical upper limits
  23. GRB 250706A: SAO RAS optical observations
  24. EP250704A: NOWT Detection
  25. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  26. The EP-WXT trigger 01709181580 is likely a flaring star
  27. GRB250706B: Swift-XRT counterpart detection
  28. GRB 250706B: iTelescope optical observations
  29. IceCube-250706A - IceCube observation of a high-energy neutrino candidate track-like event
  30. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  31. GRB 250706B: SVOM/VT optical observation
  32. GRB 250706B: TRT bright optical counterpart detection
  33. GRB 250706A: GROWTH-India Telescope optical upper limit
  34. GRB 250706B: SVOM detection of a long burst
  35. GRB 250706A: Swift detection of a burst
  36. GRB 250704B: Swift-XRT refined Analysis
  37. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  38. EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
  39. GRB 250703A: EIRSAT-1 GMOD Detection
  40. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  41. GRB 250704B: Swift/UVOT Upper Limits
  42. GRB 250704A: Swift/UVOT Detection
  43. LIGO/Virgo/KAGRA S250705cb: Identification of a GW compact binary merger candidate
  44. Radio observation of GRBs 250702B,C,E / EP250702a with the Allen Telescope Array
  45. GRB 250704B: Insight-HXMT detection
  46. Konus-Wind detection of GRB 250703A
  47. IPN triangulation of GRB 250703A
  48. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  49. EP250704a/GRB 250704B: FTW optical and NIR observations of the counterpart
  50. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  51. Konus-Wind detection of short/hard GRB 250704B/ EP250704a
  52. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  53. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  54. GRB 250702F: Kilonova-Catcher optical afterglow detection
  55. GRB 250702F: Monte Agliale Observatory optical observations
  56. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  57. EP250704a / GRB 250704B: VLT/X-shooter spectroscopic redshift z = 0.661
  58. EP250704a / GRB 250704B: JinShan optical observations
  59. GRB 250704A: SVOM/VT optical observation
  60. EP250704a / GRB 250704B: SAO RAS optical observations
  61. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  62. GRBs 250702B,D,E / EP250702a: fast fading, extremely red counterpart
  63. EP250704a / GRB 250704B: SVOM/VT optical blue counterpart
  64. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 3-Initial Localization Volume
  65. EP250704a / GRB 250704B: Pan-STARRS iz-band imaging and photometry
  66. EP 250704a: BOOTES-5 optical detection
  67. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  68. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
  69. GRB 250702A: Insight-HXMT detection
  70. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  71. GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
  72. EP250704a / GRB250704B: Swift-XRT counterpart detection
  73. GRB 250704A: Swift-XRT afterglow detection
  74. GRB 250702B / EP2050702a: FTW optical and NIR observations
  75. Konus-Wind detection of GRB 250702F
  76. EP250704a / GRB 250704B - REM observations
  77. GRB 250702F: GROWTH-India Telescope optical observations
  78. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  79. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  80. EP250702a: WFST optical observations
  81. EP250704a: COLIBRÍ optical counterpart candidate
  82. EP250704a: Einstein Probe detection of an X-ray transient
  83. GRB 250704B: SVOM/GRM observation of a short burst
  84. GRB 250702F: optical photometry from Konkoly
  85. GRB 250704A: REM detection of the optical afterglow
  86. LIGO/Virgo/KAGRA S250704ab: Coverage and upper limits from MAXI/GSC observations
  87. GRB 250702F: SVOM/VT optical observation
  88. LIGO/Virgo/KAGRA S250704ab: Identification of a GW compact binary merger candidate
  89. GRB 250704A: SVOM detection of a burst
  90. GRB 250702F: Swift/UVOT Detection
  91. GRB 250702A: CALET Gamma-Ray Burst Monitor detection
  92. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  93. Fermi GRB 250703A: Global MASTER-Net observations report
  94. GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit
  95. GRB 250702F: Swift-XRT refined Analysis
  96. GRB 250702F: Fermi GBM Observation
  97. GRB 250702F: Leavitt Observatory optical observations
  98. GRB 250702F: AKO Optical Afterglow Detection
  99. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  100. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation

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