Skip to main content
New! BOOM Notices and Schema v7.0.0. See news and announcements

GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"
  1. MAXI GRB240514.78: Global MASTER-Net observations report
  2. Fermi Gamma-ray Burst Monitor list of triggers that are not a GRB
  3. GRB 240514E: MAXI/GSC detection of a probable afterglow
  4. GRB 240514B: GRBAlpha detection
  5. LIGO/Virgo/KAGRA S240514x: Updated Sky localization
  6. LIGO/Virgo/KAGRA S240515m: Identification of a GW compact binary merger candidate
  7. GRB 240514B: Fermi GBM Detection
  8. LIGO/Virgo/KAGRA S240422ed: Las Cumbres Observatory Follow-up Observations of the Localization Region
  9. GRB 240513A: Fermi GBM observation
  10. GRB 240513A: Swift-XRT observations
  11. LIGO/Virgo/KAGRA S240513ei: Updated Sky localization
  12. LIGO/Virgo/KAGRA S240514x: Identification of a GW compact binary merger candidate
  13. GRB 240514D: AstroSat CZTI detection
  14. GRB 240514C: Fermi GBM Final Real-time Localization
  15. LIGO/Virgo/KAGRA S240514c: Identification of a GW compact binary merger candidate
  16. Fermi GRB 240514B: Global MASTER-Net observations report
  17. transient: Xinglong Nearby Galaxy Supernova Survey detection of AT2024iss
  18. Fermi Gamma-ray Burst Monitor triggers 737345659/240514093 and GRB240514A are not GRBs
  19. GRB 240514B: Fermi GBM Final Real-time Localization
  20. LIGO/Virgo/KAGRA S240507p: Upper limits from Swift/BAT-GUANO
  21. LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
  22. LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
  23. GRB 240514A: Fermi GBM Final Real-time Localization
  24. GRB 240513A: Tiled Swift observations
  25. LAT GRB240513.31: Global MASTER-Net observations report
  26. GRB 240513A: Fermi-LAT detection
  27. LIGO/Virgo/KAGRA S240513ei: Identification of a GW compact binary merger candidate
  28. GRB 240511A: Fermi GBM Observation
  29. GRB 240511A: Swift-BAT refined analysis
  30. Fermi GRB 240513B: Global MASTER-Net observations report
  31. Fermi trigger No 737277727: Global MASTER-Net observations report
  32. GRB 240513B: Fermi GBM Final Real-time Localization
  33. GRB 240513A: AstroSat CZTI detection
  34. LIGO/Virgo/KAGRA S240513cx: Coverage and upper limits from MAXI/GSC observations
  35. Fermi trigger No 737258655: Global MASTER-Net observations report
  36. GRB 240511A: J-band observations with WINTER
  37. Fermi trigger No 737247400: Global MASTER-Net observations report
  38. Fermi trigger No 737244199: Global MASTER-Net observations report
  39. Fermi trigger No 737218721: Global MASTER-Net observations report
  40. Fermi trigger No 737196587: Global MASTER-Net observations report
  41. Fermi trigger No 737168073: Global MASTER-Net observations report
  42. GRB 240511A: Enhanced Swift-XRT position
  43. GRB 240511A : MITSuME Akeno optical upper limits
  44. LIGO/Virgo/KAGRA S240512r: Updated Sky localization and EM Bright Classification
  45. GRB 240511A: Swift-XRT refined Analysis
  46. GRB 240511A: optical afterglow detection from the NOT
  47. Fermi Gamma-ray Burst Monitor trigger 737102480/240511279 is not a GRB
  48. Fermi Gamma-ray Burst Monitor trigger 737111207/240511380 is not a GRB
  49. Fermi GBM trigger 737105243/240511311 is not a GRB
  50. Fermi trigger No 737173236: Global MASTER-Net observations report
  51. LIGO/Virgo/KAGRA S240512r: Identification of a GW compact binary merger candidate
  52. Fermi GRB 240511A: Global MASTER-Net observations report
  53. Swift GRB 240511A: Global MASTER-Net observations report
  54. Fermi trigger No 737105243: Global MASTER-Net observations report
  55. Fermi Gamma-ray Burst Monitor trigger 737133200/240511634 is not a GRB
  56. Fermi trigger No 737152719: Global MASTER-Net observations report
  57. GRB 240511A: Prompt enhanced Swift-XRT position
  58. GRB 240511A: Swift detection of a burst
  59. LIGO/Virgo/KAGRA S240511i: Updated Sky localization
  60. GRB 240511A: Fermi GBM Final Real-time Localization
  61. Fermi trigger No 737102480: Global MASTER-Net observations report
  62. Fermi trigger No 737111207: Global MASTER-Net observations report
  63. LIGO/Virgo/KAGRA S240511i: Identification of a GW compact binary merger candidate
  64. Fermi Gamma-ray Burst Monitor trigger 737076431/240510977 is not a GRB
  65. LIGO/Virgo/KAGRA S240422ed: GMOS-S photometry of J-GEM24a
  66. LIGO/Virgo/KAGRA S240422ed: P200 observations of AT2024hit
  67. LIGO/Virgo/KAGRA S240422ed: Candidates from the latest GW-MMADS DECam Observations
  68. Fermi trigger No 736967879: Global MASTER-Net observations report
  69. EP240506a: Xinglong optical upper limit
  70. Fermi Gamma-ray Burst Monitor trigger 230925241/717313591 is not a GRB
  71. EP240506a: CrAO ZTSH optical upper limit
  72. GRB 240504A: Fermi GBM Observation
  73. Fermi Gamma-ray Burst Monitor trigger 736837160/240508208 is not a GRB
  74. EP240506a: Archival radio searching
  75. EP240506a: TRT optical upper limit
  76. EP240506a: BOOTES Network optical upper limit
  77. LIGO/Virgo/KAGRA S240507p: Updated Sky localization and EM Bright Classification
  78. LIGO/Virgo/KAGRA S240422ed: Upper limits from a two-week IceCube neutrino search
  79. Fermi trigger No 736733320: Global MASTER-Net observations report
  80. EP240506a: Optical upper limit with Kinder observations
  81. IPN triangulation of GRB 240504A
  82. GRB 240502A: 1.3m DFOT Optical upper limit
  83. EP240506a: EP-WXT detection of a new fast X-ray transient
  84. LIGO/Virgo/KAGRA S240507p: Identification of a GW compact binary merger candidate
  85. LIGO/Virgo/KAGRA S240422ed: Additional WINTER near-infrared J-band observations
  86. LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfr and AT2024hfs
  87. GRB 240504A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  88. Fermi GBM triggers 736668287/240506253 and 736669277/240506265 are not GRBs
  89. LIGO/Virgo/KAGRA S240505av: Updated Sky localization and EM Bright Classification
  90. Fermi trigger No 736564880: Global MASTER-Net observations report
  91. LIGO/Virgo/KAGRA S240505av: Identification of a GW compact binary merger candidate
  92. IceCube-240424A: GRANDMA Optical Upper Limit of Fermi J2151.3+0220
  93. GRB 240502C: Zeiss-1000 at Koshka observatory observations of GOTO optical counterpart candidates
  94. Fermi trigger No 736461232: Global MASTER-Net observations report
  95. IPN triangulation of GRB 240501B and GRB 240501A - possible episodes of ultra long GRB
  96. Fermi GRB 240504A: Global MASTER-Net observations report
  97. Fermi trigger No 736472503: Global MASTER-Net observations report
  98. GW170817: VLA observations at ~5.5 yrs since merger
  99. GRB 240503A: AstroSat CZTI detection
  100. GRB 240504A: BALROG localization (Fermi Trigger 736492377 / GRB 240504217)

Advanced

Download all Circulars as a .tar.gz archive:
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