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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"

16007 results found.

  1. EP250711a: COLIBRÍ continuous optical observations
  2. GRB 250713A: JinShan optical upper limits
  3. GRB 250711A: DDOTI Optical Upper Limit
  4. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate (duplicate submission)
  5. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
  6. GRB 250711A: SVOM/GRM observation
  7. EP250711a: NOT optical counterpart candidate
  8. EP candidate (ID=08500000365): COLIBRÍ optical Upper limit
  9. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  10. GRB 250702B,D,E/EP250702A: MeerKAT radio observations at 1.28GHz
  11. EP/WXT 01709181970: GOTO observations confirm stellar variability
  12. EP250704a/GRB 250704B: 10 GHz VLA detection
  13. IceCube-250706A: No Candidates from WINTER
  14. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  15. GRB 250704B / EP250704a: VLA radio detection
  16. EP250704a/GRB250704B : HCT optical and NIR upper limits
  17. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  18. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  19. GRB 250702F: radio detection with the VLA
  20. GRB 250706B/C: VLT/X-shooter redshift z = 0.942
  21. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  22. EP250702a/GRB250702 B,D,E: GRANDMA Upper Limit
  23. GRB 250706B: Swift/UVOT Detection
  24. GRB 250702F: GRANDMA observations
  25. GRB 250706B: refined SVOM/MXT data analysis
  26. GRB 250706A: Swift/UVOT Upper Limits
  27. GRB 250706B: REM optical observations
  28. GRB 250706A: REM optical/NIR observations
  29. IceCube-250416A: DDOTI Optical Upper Limit
  30. IceCube-250706A: COLIBRÍ optical upper limits
  31. GRB 250706A: JinShan optical upper limits
  32. GRB 250706A: SAO RAS optical observations
  33. EP250704A: NOWT Detection
  34. GRB250706B: Swift-XRT counterpart detection
  35. GRB 250706B: iTelescope optical observations
  36. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  37. GRB 250706B: SVOM/VT optical observation
  38. GRB 250706B: TRT bright optical counterpart detection
  39. GRB 250706A: GROWTH-India Telescope optical upper limit
  40. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  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: VLT/X-shooter spectroscopic redshift z = 0.661
  53. EP250704a / GRB 250704B: JinShan optical observations
  54. GRB 250704A: SVOM/VT optical observation
  55. EP250704a / GRB 250704B: SAO RAS optical observations
  56. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  57. GRBs 250702B,D,E / EP250702a: fast fading, extremely red counterpart
  58. EP250704a / GRB 250704B: SVOM/VT optical blue counterpart
  59. EP250704a / GRB 250704B: Pan-STARRS iz-band imaging and photometry
  60. EP 250704a: BOOTES-5 optical detection
  61. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  62. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  63. GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
  64. EP250704a / GRB250704B: Swift-XRT counterpart detection
  65. GRB 250702B / EP2050702a: FTW optical and NIR observations
  66. EP250704a / GRB 250704B - REM observations
  67. GRB 250702F: GROWTH-India Telescope optical observations
  68. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  69. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  70. EP250702a: WFST optical observations
  71. EP250704a: COLIBRÍ optical counterpart candidate
  72. GRB 250702F: optical photometry from Konkoly
  73. GRB 250704A: REM detection of the optical afterglow
  74. GRB 250702F: SVOM/VT optical observation
  75. GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit
  76. GRB 250702F: Leavitt Observatory optical observations
  77. GRB 250702F: AKO Optical Afterglow Detection
  78. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  79. GRB 250702F: Skynet Optical Observations
  80. GRB 250424A: VIRT Optical Upper Limit
  81. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  82. GRB 250702F: TRT Optical Observation
  83. GRB 250703A: DDOTI Optical Upper Limit
  84. GRB 250702F: REM optical afterglow detection
  85. GRB 250702F: DDOTI Optical Observation
  86. EP250702a/GRB 250702B,C,D,E: GOTO optical upper limits
  87. GRB 250702F: COLIBRÍ Observations of the Afterglow
  88. GRB 250702F: GTC/OSIRIS+ spectroscopic redshift z = 1.520
  89. GRB 250702F: NOT observations of the optical afterglow
  90. GRB 250702F: MASTER optical afterglow observation
  91. GRB 250702F: GOTO optical counterpart detection
  92. GRB 250702F: Ondrejov D50 optical afterglow detection
  93. GRB 250702F: Swift detection of a burst with an optical counterpart
  94. GRB 250628B: SVOM/VT optical upper limit
  95. GRB 250628A: REM optical/NIR upper limits
  96. GRB 250628B: SVOM detection of a long burst
  97. GRB 250625A: VLT/X-shooter spectroscopic observations at the afterglow position
  98. GRB 250628A: Swift/UVOT Upper Limits
  99. GRB 250625A: Leavitt Observatory afterglow detection
  100. GRB 250625A: AbAO and INASAN Kislovodsk Optical Observations

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