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"

21929 results found.

  1. GRB 250628A: Swift/UVOT Upper Limits
  2. Fermi GRB 250626A: Global MASTER-Net observations report
  3. Swift GRB 250628A: Global MASTER-Net observations report
  4. GRB 250625A: Leavitt Observatory afterglow detection
  5. GRB 250625A: AbAO and INASAN Kislovodsk Optical Observations
  6. GRB 250625A: GTC/OSIRIS+ spectroscopic observations of the potential host galaxy
  7. GRB 250625A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  8. GRB 250625A: SVOM/C-GFT upper limit in early phase
  9. GRB 250625A: Swift/UVOT Upper Limits
  10. GRB 250625A: ABObservatory afterglow detection
  11. GRB 250625A: OHP/T193 optical detection
  12. GRB 250625A: COLIBRÍ optical observations
  13. GRB 250625A: JinShan optical observations
  14. Swift GRB 250625A: Global MASTER-Net observations report
  15. GRB 250625A: SAO RAS possible optical afterglow
  16. Fermi GRB 250625A: Global MASTER-Net observations report
  17. GRB 250617B: Mondy and SAO RAS optical observations on 2025-06-23, 2025-06-24
  18. GRB 241018A: Maidanak optical observations
  19. Fermi GRB 250624A: Global MASTER-Net observations report
  20. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  21. Fermi GRB 250623A: Global MASTER-Net observations report
  22. Fermi trigger No 772190032: Global MASTER-Net observations report
  23. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  24. Fermi GRB 250621A: Global MASTER-Net observations report
  25. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  26. GRB 250506A - SVOM/ECLAIRs Refined analysis
  27. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  28. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  29. Fermi trigger No 772128434: Global MASTER-Net observations report
  30. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  31. GRB 250617B: Nickel telescope optical observations
  32. Fermi trigger No 772058337: Global MASTER-Net observations report
  33. GRB 250615A: Kilonova-Catcher optical upper limits
  34. GRB 250617B: Assy AZT-20 Optical Observations
  35. GRB 250612A / Swift J1643.6−3854: Swift-BAT refined analysis
  36. Fermi GRB 250617A: Global MASTER-Net observations report
  37. GRB 250615A/EP250615a: FTW optical and NIR observations
  38. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  39. GRB 250617B: Swift/UVOT Detection
  40. GRB 250617B: Kilonova-Catcher optical afterglow detection
  41. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  42. GRB 250617B: COLIBRÍ optical observations
  43. GRB 250617B: NOT NIR observations of the afterglow
  44. GRB 250617B: NUTTelA-TAO early time optical observations
  45. Fermi trigger No 771886893: Global MASTER-Net observations report
  46. Swift GRB 250617B: Global MASTER-Net observations report
  47. GRB 250617B: GOTO optical upper limit
  48. GRB 250617B: SAO RAS optical observations
  49. GRB 250615A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  50. EP#01709178975: Swift-XRT counterpart detection
  51. EP-WXT trigger 01709178975: GOTO optical upper limit
  52. SVOM sb25061207: AbAO AS-32 Optical Upper Limit
  53. GRB 250615A: DDOTI Optical Upper Limit
  54. GRB 250615A: Swift/UVOT Upper Limits
  55. Fermi trigger No 771752663: Global MASTER-Net observations report
  56. Swift GRB 250615A: Global MASTER-Net observations report
  57. Fermi trigger No 771718064: Global MASTER-Net observations report
  58. sb25061207: Mephisto optical upper limits
  59. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
  60. Fermi trigger No 771494087: Global MASTER-Net observations report
  61. sb25061218: Swift-XRT observations
  62. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  63. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  64. Fermi trigger No 771424081: Global MASTER-Net observations report
  65. EP250612a: Global MASTER-Net observations report
  66. sb25061207: Swift-XRT observations
  67. EP250612a/GRB 250612B: JinShan optical upper limit
  68. EP250610a: Upper limit from Fermi-GBM Observations
  69. GRB 250610B: Liverpool Telescope continued monitoring
  70. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  71. EP250610a: continuous follow-up observations with EP-FXT
  72. GRB 250610B - SVOM/ECLAIRs refined analysis
  73. Swift GRB250612.04: Global MASTER-Net observations report
  74. Fermi GBM Sub-Threshold Detection of GRB 250610B
  75. GRB 250610B: Swift/UVOT Detection
  76. EP250610A: Swift/UVOT Upper limits
  77. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  78. GRB 250610B: REM optical/NIR observations
  79. GRB 250610B: SVOM/VT optical shallow decay
  80. GRB 250610B: additional Liverpool Telescope optical observations
  81. GRB 250610B: Swift-XRT counterpart detection
  82. GRB 250610B: LT detection of the optical counterpart
  83. GRB 250610B: GOTO optical upper limit
  84. EP250610a: Global MASTER-Net observations report
  85. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  86. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  87. EP250610a: REM optical/NIR observations
  88. EP250610a: Swift-XRT counterpart detection
  89. EP250610a: COLIBRÍ optical upper limit
  90. Fermi trigger No 771072240: Global MASTER-Net observations report
  91. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  92. GRB 250605A: Swift/UVOT Upper Limits
  93. GRB 250529A: GOTO optical counterpart candidate (GOTO25dea/AT 2025ndt)
  94. GRB 250527C: CrAO Optical Upper Limit
  95. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  96. EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  97. GRB 250605A: SVOM/VT optical upper limit
  98. EP/WXT 01709177873: GOTO observations confirm stellar variability
  99. Fermi GRB 250606A: Global MASTER-Net observations report
  100. Fermi trigger No 770867684: Global MASTER-Net observations report

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