Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! 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"

22053 results found.

  1. LIGO/Virgo/KAGRA S240525p: Upper limits from Swift/BAT-GUANO
  2. GRB 240529A: J-band detections with WINTER
  3. GRB 240529A: Skynet Optical Observations
  4. LXT 240528A: LEIA detection of a fast X-ray transient
  5. LIGO/Virgo S240527fv: GRANDMA/FRAM-Auger Optical Observations
  6. GRB 240529A: Swift/UVOT Detection
  7. GRB 240529A: NOT optical observations
  8. GRB 240529A: GOTO optical afterglow detection
  9. GRB 240527B: Swift-XRT afterglow detection
  10. Swift GRB240529.12: Global MASTER-Net observations report
  11. Fermi GRB 240527A: Global MASTER-Net observations report
  12. LAT GRB240527.59: Global MASTER-Net observations report
  13. Fermi GRB 240527B: Global MASTER-Net observations report
  14. Fermi trigger No 738348224: Global MASTER-Net observations report
  15. Fermi trigger No 738330463: Global MASTER-Net observations report
  16. GRB 240513A: Swift-XRT afterglow detection
  17. GRB 240521B: Swift/BAT-GUANO arcminute localization of a long burst
  18. Fermi trigger No 737996942: Global MASTER-Net observations report
  19. EP240518a: GSP optical upper limit
  20. LIGO/Virgo/KAGRA S240515m: Upper limits from Swift/BAT-GUANO
  21. LIGO/Virgo/KAGRA S240514x: Upper limits from Swift/BAT-GUANO
  22. LIGO/Virgo/KAGRA S240513ei: Upper limits from Swift/BAT-GUANO
  23. GRB 240516A: Swift/UVOT Upper Limits
  24. Fermi trigger No 737788024: Global MASTER-Net observations report
  25. EP240518a: EP-WXT detection of a new X-ray transient
  26. Fermi GRB 240517A: Global MASTER-Net observations report
  27. GRB 240516A ATCA radio observations
  28. GRB 240513A: Swift ToO observations
  29. GRB 240514E: A possible candidate BD-21 1074
  30. Fermi trigger No 737559855: Global MASTER-Net observations report
  31. GRB 240511A: Observations from GTC/OSIRIS+
  32. GRB 240502C: Zeiss-1000 at Koshka observations of GOTO24bao optical counterpart candidate
  33. Fermi trigger No 737523389: Global MASTER-Net observations report
  34. Swift GRB240516.15: Global MASTER-Net observations report
  35. Fermi trigger No 737476171: Global MASTER-Net observations report
  36. GRB 240511A: radio detection of afterglow candidate
  37. GRB 240514B: GOTO candidate optical counterpart
  38. MAXI GRB240514.78: Global MASTER-Net observations report
  39. LIGO/Virgo/KAGRA S240515m: Identification of a GW compact binary merger candidate
  40. LIGO/Virgo/KAGRA S240422ed: Las Cumbres Observatory Follow-up Observations of the Localization Region
  41. GRB 240513A: Swift-XRT observations
  42. Fermi GRB 240514B: Global MASTER-Net observations report
  43. transient: Xinglong Nearby Galaxy Supernova Survey detection of AT2024iss
  44. LIGO/Virgo/KAGRA S240507p: Upper limits from Swift/BAT-GUANO
  45. LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
  46. LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
  47. GRB 240513A: Tiled Swift observations
  48. LAT GRB240513.31: Global MASTER-Net observations report
  49. Fermi GRB 240513B: Global MASTER-Net observations report
  50. Fermi trigger No 737277727: Global MASTER-Net observations report
  51. LIGO/Virgo/KAGRA S240513cx: Coverage and upper limits from MAXI/GSC observations
  52. Fermi trigger No 737258655: Global MASTER-Net observations report
  53. GRB 240511A: J-band observations with WINTER
  54. Fermi trigger No 737247400: Global MASTER-Net observations report
  55. Fermi trigger No 737244199: Global MASTER-Net observations report
  56. Fermi trigger No 737218721: Global MASTER-Net observations report
  57. Fermi trigger No 737196587: Global MASTER-Net observations report
  58. Fermi trigger No 737168073: Global MASTER-Net observations report
  59. GRB 240511A: optical afterglow detection from the NOT
  60. Fermi trigger No 737173236: Global MASTER-Net observations report
  61. Fermi GRB 240511A: Global MASTER-Net observations report
  62. Swift GRB 240511A: Global MASTER-Net observations report
  63. Fermi trigger No 737105243: Global MASTER-Net observations report
  64. Fermi trigger No 737152719: Global MASTER-Net observations report
  65. Fermi trigger No 737102480: Global MASTER-Net observations report
  66. Fermi trigger No 737111207: Global MASTER-Net observations report
  67. LIGO/Virgo/KAGRA S240422ed: GMOS-S photometry of J-GEM24a
  68. LIGO/Virgo/KAGRA S240422ed: P200 observations of AT2024hit
  69. LIGO/Virgo/KAGRA S240422ed: Candidates from the latest GW-MMADS DECam Observations
  70. Fermi trigger No 736967879: Global MASTER-Net observations report
  71. EP240506a: CrAO ZTSH optical upper limit
  72. EP240506a: Archival radio searching
  73. EP240506a: TRT optical upper limit
  74. Fermi trigger No 736733320: Global MASTER-Net observations report
  75. EP240506a: Optical upper limit with Kinder observations
  76. EP240506a: EP-WXT detection of a new fast X-ray transient
  77. LIGO/Virgo/KAGRA S240422ed: Additional WINTER near-infrared J-band observations
  78. LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfr and AT2024hfs
  79. GRB 240504A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  80. Fermi trigger No 736564880: Global MASTER-Net observations report
  81. IceCube-240424A: GRANDMA Optical Upper Limit of Fermi J2151.3+0220
  82. GRB 240502C: Zeiss-1000 at Koshka observatory observations of GOTO optical counterpart candidates
  83. Fermi trigger No 736461232: Global MASTER-Net observations report
  84. Fermi GRB 240504A: Global MASTER-Net observations report
  85. Fermi trigger No 736472503: Global MASTER-Net observations report
  86. GW170817: VLA observations at ~5.5 yrs since merger
  87. Fermi trigger No 736387941: Global MASTER-Net observations report
  88. LXT 240402A / GRB 240402B: VLT X-shooter redshift of host
  89. GRB 240502A: GOTO optical upper limit
  90. Fermi trigger No 736379109: Global MASTER-Net observations report
  91. GRB 240502C: GOTO possible optical counterpart candidates
  92. Fermi GRB 240502B: Global MASTER-Net observations report
  93. Fermi GRB 240502A: Global MASTER-Net observations report
  94. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet Transient Candidates
  95. Integral GRB240502.23: Global MASTER-Net observations report
  96. LIGO/Virgo/KAGRA S240422ed: Host redshifts of AT2024hfq, AT2024hfu, and AT2024hmo from DBSP
  97. Fermi GRB 240501A: Global MASTER-Net observations report
  98. Fermi trigger No 736197684: Global MASTER-Net observations report
  99. MeerKAT Discovery of a Probable Radio Counterpart to EP240414a
  100. LIGO/Virgo/KAGRA S240422ed: GECKO/7DT ToO observations

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