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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"

21930 results found.

  1. EP/WXT 01709181970: GOTO observations confirm stellar variability
  2. EP250704a/GRB 250704B: 10 GHz VLA detection
  3. GRB250702 B,D,E / EP250702a: MOSFIRE imaging of the afterglow
  4. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 4-Update Localization Volume
  5. IceCube-250706A: No Candidates from WINTER
  6. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  7. GRB 250704B / EP250704a: VLA radio detection
  8. Fermi GRB 250708A: Global MASTER-Net observations report
  9. IceCube-250708A: Global MASTER-Net observations report
  10. EP250704a/GRB250704B : HCT optical and NIR upper limits
  11. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  12. GRB 250704B: CALET Gamma-Ray Burst Monitor detection
  13. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  14. GRB 250702F: radio detection with the VLA
  15. IceCube-250706A: EP-FXT follow-up observations
  16. Fermi-LAT Gamma-ray Observations of IceCube-250706A
  17. IceCube-250706A: Global MASTER-Net observations report
  18. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  19. EP250702a/GRB250702 B,D,E: GRANDMA Upper Limit
  20. GRB 250706B: Swift/UVOT Detection
  21. EP250702a/ GRB 250702B: NuSTAR X-ray Observations
  22. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  23. GRB 250702F: GRANDMA observations
  24. GRB 250706B: refined SVOM/MXT data analysis
  25. GRB 250706A: Swift/UVOT Upper Limits
  26. GRB 250706B: REM optical observations
  27. GRB 250706A: REM optical/NIR observations
  28. IceCube-250416A: DDOTI Optical Upper Limit
  29. IceCube-250706A: COLIBRÍ optical upper limits
  30. Swift GRB 250706A: Global MASTER-Net observations report
  31. GRB 250706A: JinShan optical upper limits
  32. GRB 250706A: SAO RAS optical observations
  33. EP250704A: NOWT Detection
  34. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  35. GRB250706B: Swift-XRT counterpart detection
  36. GRB 250706B: iTelescope optical observations
  37. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  38. GRB 250706B: TRT bright optical counterpart detection
  39. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  40. EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
  41. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  42. GRB 250704B: Swift/UVOT Upper Limits
  43. GRB 250704A: Swift/UVOT Detection
  44. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  45. EP250704a/GRB 250704B: FTW optical and NIR observations of the counterpart
  46. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  47. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  48. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  49. GRB 250702F: Kilonova-Catcher optical afterglow detection
  50. GRB 250702F: Monte Agliale Observatory optical observations
  51. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  52. EP250704a / GRB 250704B: JinShan optical observations
  53. EP250704a / GRB 250704B: SAO RAS optical observations
  54. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  55. GRBs 250702B,D,E / EP250702a: fast fading, extremely red counterpart
  56. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 3-Initial Localization Volume
  57. EP250704a / GRB 250704B: Pan-STARRS iz-band imaging and photometry
  58. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  59. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
  60. GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
  61. EP250704a / GRB250704B: Swift-XRT counterpart detection
  62. GRB 250702B / EP2050702a: FTW optical and NIR observations
  63. EP250704a / GRB 250704B - REM observations
  64. GRB 250702F: GROWTH-India Telescope optical observations
  65. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  66. EP250702a: WFST optical observations
  67. EP250704a: COLIBRÍ optical counterpart candidate
  68. GRB 250702F: optical photometry from Konkoly
  69. GRB 250704A: REM detection of the optical afterglow
  70. LIGO/Virgo/KAGRA S250704ab: Coverage and upper limits from MAXI/GSC observations
  71. GRB 250702F: Swift/UVOT Detection
  72. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  73. Fermi GRB 250703A: Global MASTER-Net observations report
  74. GRB 250702F: Leavitt Observatory optical observations
  75. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  76. GRB 250702F: Skynet Optical Observations
  77. GRBs 250702B/C/D/E / EP250702a: Swift XRT localization
  78. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  79. GRB 250702F: TRT Optical Observation
  80. GRB 250703A: DDOTI Optical Upper Limit
  81. GRB 250702F: REM optical afterglow detection
  82. EP250702a: Global MASTER-Net observations report
  83. GRB 250702F: DDOTI Optical Observation
  84. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  85. EP250702a/GRB 250702B,C,D,E: GOTO optical upper limits
  86. GRB 250702F: COLIBRÍ Observations of the Afterglow
  87. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  88. Fermi GRB 250702E: Global MASTER-Net observations report
  89. Fermi GRB 250702B: Global MASTER-Net observations report
  90. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  91. GRB 250702F: GTC/OSIRIS+ spectroscopic redshift z = 1.520
  92. GRB 250702F: NOT observations of the optical afterglow
  93. Fermi GRB 250702F: Global MASTER-Net observations report
  94. Fermi GRB 250702C: Global MASTER-Net observations report
  95. GRB 250702F: GOTO optical counterpart detection
  96. GRB 250702F: Ondrejov D50 optical afterglow detection
  97. Swift GRB 250702F: Global MASTER-Net observations report
  98. GRB 250628B: Swift-XRT observations
  99. GRB 250628B: SVOM/VT optical upper limit
  100. GRB 250628A: REM optical/NIR upper limits

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