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"

32717 results found.

  1. GRB 250912A: SVOM/GRM analysis suggests a possible short GRB with extended emission
  2. GRB 250912A:SVOM/VT optical upper limit
  3. GRB 250912A: LCO optical upper limit
  4. Fermi GRB 250912A: Global MASTER-Net observations report
  5. EP250911a: Global MASTER-Net observations report
  6. GRB 250912A: SVOM detection of a burst
  7. EP250908c: tentative VLT/FORS2 redshift z = 2.87
  8. EP250911a: Upper limit from Fermi-GBM Observations
  9. LIGO/Virgo/KAGRA S250912f: Updated Sky localization
  10. GRB 250911A: GECAM-B detection
  11. GRB 250911A: Swift-BAT refined analysis
  12. EP250911a: GTC/OSIRIS+ spectroscopic redshift z = 3.84
  13. LIGO/Virgo/KAGRA S250912f: Identification of a GW compact binary merger candidate
  14. EP250911a: refined analysis of the EP-WXT and EP-FXT observations
  15. GRB 250910B: SVOM/GRM observation
  16. EP250911a: SVOM/VT optical observation
  17. GRB 250911A: MASTER optical counterpart observations
  18. EP250911a: SAO RAS optical observations
  19. EP250911a: Swift-XRT observations
  20. EP250911a: Optical detection with Kinder observations
  21. GRB 250911A: Swift/UVOT Detection
  22. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  23. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  24. GRB 250909B: Insight-HXMT detection
  25. GRB 250909B: SVOM/GRM observation
  26. LIGO/Virgo/KAGRA S250911ac: Updated Sky localization and Source Classification
  27. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  28. EP250911a: COLIBRÍ optical observations
  29. LIGO/Virgo/KAGRA S250908y: Updated Sky localization
  30. Fermi GRB 250910B: Global MASTER-Net observations report
  31. EP250911a: LCO optical counterpart discovery
  32. EP250910a: Global MASTER-Net observations report
  33. GRB 250404A / EP250404a: spectroscopic redshift at z = 1.88 (correction to GCN 40084)
  34. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  35. GRB 250903A: SVOM/ECLAIRs refined analysis
  36. GRB 250911A: COLIBRÍ optical counterpart candidate
  37. LIGO/Virgo/KAGRA S250906ca: Updated Sky localization
  38. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  39. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  40. GRB 250910A: SVOM/VT optical upper limit
  41. EP250908C: GROND observation of the fading optical counterpart
  42. GRB 250910A: LCO optical upper limit
  43. GRB 250909A: AstroSat CZTI detection
  44. GRB 250910A: SVOM/MXT possible afterglow detection
  45. GRB 250702B: Late time Chandra observations
  46. EP250908b/EP#01709240653: Swift/UVOT Detection
  47. EP250908c: refined analysis of the EP-WXT and EP-FXT observations
  48. GRB 250907A: CALET Gamma-Ray Burst Monitor detection
  49. EP250908c: SVOM/VT optical observation
  50. EP250908c: VLT/FORS2 optical counterpart identification
  51. EP250908b: SVOM/VT optical candidate (Coordinate supplement for GCN 41758)
  52. EP250908b: SVOM/VT optical candidate
  53. EP250908c: Global MASTER-Net observations report
  54. Fermi GRB 250909A: Global MASTER-Net observations report
  55. LIGO/Virgo/KAGRA S250908y: Identification of a GW compact binary merger candidate
  56. GRB 250905A: Swift-BAT refined analysis
  57. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  58. GRB 250903A: Swift-XRT afterglow detection
  59. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  60. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  61. EP250905a: Liverpool Telescope i-band upper limits
  62. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  63. EP250905b: EP-FXT follow-up observation
  64. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 2 Candidates
  65. EP250905a: Liverpool Telescope observations
  66. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  67. EP250905b: Global MASTER-Net observations report
  68. EP250905a: FTW one optical and multiple NIR counterpart candidates
  69. EP250905a: JinShan likely optical counterpart detection
  70. GRB 250904A: Swift-BAT refined analysis
  71. GRB 250905A: Swift/UVOT Upper Limits
  72. EP250905a: Global MASTER-Net observations report
  73. GRB 250901A - SVOM/ECLAIRs refined analysis
  74. GRB250904A: Liverpool Telescope upper limits
  75. GRB 250904A: Swift/UVOT Detection
  76. GRB 250903A: Swift/UVOT detection
  77. LIGO/Virgo/KAGRA S250904cv: Updated Sky localization
  78. LIGO/Virgo/KAGRA S250904br: Updated Sky localization
  79. GRB 250905A: KAIT optical upper limit
  80. Swift GRB 250904A: Global MASTER-Net observations report
  81. GRB 250904A: TRT optical counterpart detection
  82. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  83. GRB 250902B: CALET Gamma-Ray Burst Monitor detection
  84. EP250827b: Gemini Spectroscopic Confirmation of AT2025wkm as a Ic-BL Supernova
  85. GRB 250902A: CALET Gamma-Ray Burst Monitor detection
  86. LIGO/Virgo/KAGRA S250904ae: Updated Sky localization
  87. GRB 250902A: VZLUSAT-2 detection
  88. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  89. GRB 250903A: Swift-XRT observations
  90. EP250903a: Swift-XRT observations
  91. EP#01709201209: Swift-XRT observations
  92. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  93. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  94. GRB 250830C: VZLUSAT-2 detection
  95. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  96. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  97. GRB 250903A: VLT X-shooter spectroscopic redshift z = 1.590
  98. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  99. GRB 250903A: EP-FXT counterpart detection
  100. GRB 250902A: GECAM-B detection

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Looking for U.S. government information and services? Visit USA.gov