Skip to main content
New! Browse Circulars by Event, Advanced Search, Sample Codes, Schema Release. 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"

827 results found.

  1. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  2. LIGO/Virgo/KAGRA S250704ab: Coverage and upper limits from MAXI/GSC observations
  3. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  4. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  5. GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
  6. GRB 250702B,C,D,E / EP 250702: MAXI/GSC detection
  7. GRB 250625A: Swift/UVOT Upper Limits
  8. GRB 250620A: AstroSat CZTI detection
  9. GRB 250527B: Swift-XRT observations
  10. GRB 250527B: Tiled Swift observations
  11. GRB 250527B / MAXI J1450-527 : MAXI/GSC detection
  12. MAXI GRB250515.65: Global MASTER-Net observations report
  13. GRB 250507B: AstroSat CZTI detection
  14. EP#01709175213/IGR J19566+0326: Swift-XRT detection
  15. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  16. GRB 250331A: MAXI/GSC detection
  17. EP250311a/GRB 250311A: Correction to EP-WXT detection time
  18. EP250311a/GRB 250311A: EP-FXT follow-up observation
  19. GRB 250311A: Swift-XRT observations
  20. GRB 250311A/EP250311a: TRT optical upper limit
  21. GRB 250311A: Tiled Swift observations
  22. EP250311a/GRB 250311A: EP-WXT detection
  23. GRB 250311A/MAXI J1457-026: MAXI/GSC detection
  24. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  25. GRB 250207B: Swift-XRT observations
  26. GRB 250207B: Tiled Swift observations
  27. GRB 250207B: MAXI/GSC detection
  28. LIGO/Virgo/KAGRA S250206dm: Coverage and upper limits from MAXI/GSC observations
  29. LIGO/Virgo/KAGRA S250201i: Coverage and upper limits from MAXI/GSC observations
  30. Fermi GRB 250128A: Global MASTER-Net observations report
  31. GRB 250126A: CALET Gamma-Ray Burst Monitor detection
  32. GRB 250126A: MAXI/GSC detection
  33. LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
  34. GRB 241213B: Swift-XRT observations
  35. GRB 241213B: Tiled Swift observations
  36. GRB 241213B: CALET Gamma-Ray Burst Monitor detection
  37. GRB 241213B: MAXI/GSC detection
  38. GRB 241207C: MASTER optical observations
  39. GRB 241207C: Tiled Swift observations
  40. GRB 241207C: MAXI/GSC detection
  41. LIGO/Virgo/KAGRA S241114bi: Coverage and upper limits from MAXI/GSC observations
  42. LIGO/Virgo/KAGRA S241109bn: Coverage and upper limits from MAXI/GSC observations
  43. LIGO/Virgo/KAGRA S240915b: Coverage and upper limits from MAXI/GSC observations
  44. LIGO/Virgo/KAGRA S240910ci: Coverage and upper limits from MAXI/GSC observations
  45. LIGO/Virgo/KAGRA S240830gn: Coverage and upper limits from MAXI/GSC observations
  46. GRB 240824B: Ondrejov D50 optical limit
  47. GRB 240824B: Fermi GBM Observation
  48. GRB 240824B: Swift-XRT afterglow detection
  49. GRB 240824B: Swift/BAT arcminute localization of a burst
  50. GRB 240824B: MAXI/GSC detection
  51. GRB 240809B: MAXI/GSC detection
  52. LIGO/Virgo/KAGRA S240711cm: Coverage and upper limits from MAXI/GSC observations
  53. LIGO/Virgo/KAGRA S240629by: Coverage and upper limits from MAXI/GSC observations
  54. GRB 240514E: A possible candidate BD-21 1074
  55. MAXI GRB240514.78: Global MASTER-Net observations report
  56. GRB 240514E: MAXI/GSC detection of a probable afterglow
  57. LIGO/Virgo/KAGRA S240513cx: Coverage and upper limits from MAXI/GSC observations
  58. LIGO/Virgo/KAGRA S240422ed: Coverage and upper limits from MAXI/GSC observations
  59. GRB 240309A: MAXI/GSC detection
  60. GRB 240225B: Swift-XRT afterglow detection
  61. GRB 240225B: Glowbug gamma-ray detection
  62. GRB 240225B: Swift ToO observations
  63. Konus-Wind detection of GRB 240225B (long)
  64. GRB 240225B: VLT/X-shooter redshift
  65. GRB 240225B : MITSuME Akeno optical afterglow candidate detection
  66. GRB 240225B: 3.6m DOT observation
  67. GRB 240225B: NOT optical observations
  68. GRB 240225B: Nanshan/HMT optical afterglow detection
  69. GRB 240225B: CALET Gamma-Ray Burst Monitor detection
  70. GRB 240225B: Swift-XRT observations
  71. GRB 240225B: GOTO detection of a candidate optical afterglow
  72. GRB 240225B: AstroSat CZTI detection
  73. GRB 240225B: Tiled Swift observations
  74. GRB 240225B: MAXI/GSC detection
  75. GRB 240128A: Further Swift-XRT observations
  76. GRB 240214A: Tiled Swift observations
  77. GRB 240214A/1H 0451-560: MAXI/GSC detection
  78. GRB 240128A: Glowbug gamma-ray detection
  79. GRB 240128A: Swift-XRT observations
  80. GRB 240128A: GRBAlpha detection
  81. GRB 240128A: Tiled Swift observations
  82. GRB 240128A: CALET Gamma-Ray Burst Monitor detection
  83. GRB 240128A: MAXI/GSC detection
  84. GRB 240122A: ATCA detection of radio counterpart
  85. GRB240122A: PRIME near infrared detection
  86. GRB 240122A: Swift/UVOT Upper Limits
  87. GRB 240122A: BOOTES-2/TELMA optical upper limit and 1.5m OSN detection
  88. Swift GRB240123.46: Global MASTER-Net observations report
  89. GRB 240122A: Swift-XRT afterglow detection
  90. GRB 240122A: VLT/X-shooter redshift confirmation
  91. GRB 240122A: Redshift from OSIRIS+/GTC
  92. GRB 240122A: LT non-detection of GOTO candidate counterpart confirms fading
  93. GRB 240122A: GOTO optical counterpart candidate
  94. GRB 240122A: Tiled Swift observations
  95. GRB 240122A: MAXI/GSC detection
  96. GRB 240107A: VZLUSAT-2 detection
  97. GRB 240114A: MAXI/GSC detection
  98. GRB 240107A: AstroSat CZTI detection
  99. GRB 240107A: MAXI/GSC detection
  100. IPN triangulation of GRB 231129C

Advanced

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