Skip to main content
JSON Notices via Email, Kafka Cron Jobs, Submitter Profile, GCN is Hiring. See news and announcements

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"

20510 results found.

  1. GRB 250704A: SVOM detection of a burst
  2. GRB 250702F: Swift/UVOT Detection
  3. GRB 250702F: Leavitt Observatory optical observations
  4. GRB 250702F: AKO Optical Afterglow Detection
  5. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  6. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  7. GRB 250702F: Skynet Optical Observations
  8. GRB 250424A: VIRT Optical Upper Limit
  9. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  10. GRB 250702F: TRT Optical Observation
  11. GRB 250703A: DDOTI Optical Upper Limit
  12. GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
  13. GRB 250702F: REM optical afterglow detection
  14. GRB 250702F: DDOTI Optical Observation
  15. GRB 250702F: COLIBRÍ Observations of the Afterglow
  16. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  17. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  18. GRB 250702F: Enhanced Swift-XRT position
  19. GRB 250702F: NOT observations of the optical afterglow
  20. GRB 250702F: Ondrejov D50 optical afterglow detection
  21. GRB 250702F: Swift detection of a burst with an optical counterpart
  22. LIGO/Virgo/KAGRA S250702n: Identification of a GW compact binary merger candidate
  23. LIGO/Virgo/KAGRA S250701bq: Identification of a GW compact binary merger candidate
  24. GRB 250628B: EP-FXT counterpart detection
  25. LIGO/Virgo/KAGRA S250629bs: Identification of a GW compact binary merger candidate
  26. LIGO/Virgo/KAGRA S250629ae: Identification of a GW compact binary merger candidate
  27. GRB 250628A: REM optical/NIR upper limits
  28. LIGO/Virgo/KAGRA S250628am: Identification of a GW compact binary merger candidate
  29. GRB 250625A: VLT/X-shooter spectroscopic observations at the afterglow position
  30. GRB 250628A: VLT/X-shooter upper limits
  31. GRB 250628A: Swift/UVOT Upper Limits
  32. GRB 250628A: Enhanced Swift-XRT position
  33. GRB 250628A: Swift detection of a burst
  34. GRB 250625A: Leavitt Observatory afterglow detection
  35. GRB 250625A: AbAO and INASAN Kislovodsk Optical Observations
  36. GRB 250625A: SVOM/C-GFT upper limit in early phase
  37. GRB 250625A: GECAM-B detection
  38. GRB 250625A: Swift/UVOT Upper Limits
  39. GRB 250625A: ABObservatory afterglow detection
  40. GRB 250625A: OHP/T193 optical detection
  41. GRB 250625A: COLIBRÍ optical observations
  42. GRB 250625A: Swift-XRT refined Analysis
  43. GRB 250625A: JinShan optical observations
  44. GRB 250625A: SAO RAS possible optical afterglow
  45. GRB 250625A: Enhanced Swift-XRT position
  46. GRB 250625A: Swift detection of a burst
  47. GRB 250617B: Mondy and SAO RAS optical observations on 2025-06-23, 2025-06-24
  48. GRB 241018A: Maidanak optical observations
  49. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  50. IPN triangulation of GRB 250620C (long/bright)
  51. GRB 250620C: SVOM/GRM observation
  52. GRB 250620A: SVOM/GRM observation of a short burst
  53. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  54. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  55. GRB 250506A - SVOM/ECLAIRs Refined analysis
  56. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  57. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  58. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  59. GRB 250617B: Nickel telescope optical observations
  60. GRB 250615A: Kilonova-Catcher optical upper limits
  61. GRB 250617B: Assy AZT-20 Optical Observations
  62. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  63. GRB 250617B: Swift/UVOT Detection
  64. GRB 250617B: Kilonova-Catcher optical afterglow detection
  65. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  66. GRB 250617B: COLIBRÍ optical observations
  67. GRB 250617B: NOT NIR observations of the afterglow
  68. GRB 250617B: NUTTelA-TAO early time optical observations
  69. GRB 250617B: Enhanced Swift-XRT position
  70. GRB 250617B: SAO RAS optical observations
  71. GRB 250617B: Swift detection of a burst with an optical counterpart
  72. GRB 250615A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  73. EP-WXT trigger 01709178975: GOTO optical upper limit
  74. Konus-Wind detection of GRB 250615A / EP250615a
  75. SVOM sb25061207: AbAO AS-32 Optical Upper Limit
  76. GRB 250615A: COLIBRÍ optical upper limit
  77. GRB 250615A: DDOTI Optical Upper Limit
  78. GRB 250615A: Swift/UVOT Upper Limits
  79. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  80. GRB 250615A: Swift-XRT refined Analysis
  81. sb25061207/SVOM: T120 OHP optical upper limit
  82. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  83. GRB 250615A: Enhanced Swift-XRT position
  84. GRB 250615A: Swift detection of a burst
  85. GRID detection of GRB 250612C
  86. sb25061207: Mephisto optical upper limits
  87. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
  88. sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  89. sb25061207: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  90. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  91. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  92. EP250612a / GRB 250612B: SVOM/VT optical candidate
  93. GRB 250612C: Fermi GBM Observation
  94. sb25061207: Swift-XRT observations
  95. EP250612a/GRB 250612B: JinShan optical upper limit
  96. sb25061207: SVOM/VT optical counterpart
  97. GRB 250610B: Swift-XRT refined Analysis
  98. EP250612a: Einstein Probe detection of an X-ray transient
  99. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  100. sb25061207: SVOM detection of a X-ray transient

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov