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"

23575 results found.

  1. GRB 250313A: Fermi GBM Detection
  2. GRB 250313A: CALET Gamma-Ray Burst Monitor detection
  3. GRB 250313A: Swift-XRT observations
  4. GRB250314A: SVOM/VT lack of bright optical candidate from VHF data
  5. Konus-Wind detection of GRB 250313A
  6. Konus-Wind detection of GRB 250308A
  7. GRB 250314A: SVOM detection of a burst
  8. GRB 250313A: AstroSat CZTI detection of a bright long burst
  9. GRB 250313A: Fermi-LAT detection
  10. EP250304a: Pan-STARRS r and i-band imaging and photometry
  11. EP trigger ID 01709061302: Lick/Kast spectroscopy with the 3 m Shane telescope
  12. GRB 250312A: Swift-XRT refined Analysis
  13. GRB 250302A: Fermi GBM Observation
  14. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  15. GRB 250312A: Swift detection of a burst
  16. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  17. GRB 250311A: Swift-XRT observations
  18. GRB 250228A: Fermi GBM Observation
  19. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  20. GRB 250225B: Swift-BAT refined analysis
  21. GRB 250311A/EP250311a: TRT optical upper limit
  22. IceCube-250309A: MITSuME Akeno and Seimei/TriCCS optical observations
  23. GRB 250308A: CALET Gamma-Ray Burst Monitor detection
  24. GRB 250311B: SVOM detection of a burst
  25. GRB 250309B: SVOM/VT optical observation
  26. GRB 250311A/MAXI J1457-026: MAXI/GSC detection
  27. GRB 250309B / AT2025dws: further SAO RAS optical observations
  28. EP250308a: 1.6m Mephisto optical upper limits
  29. Konus-Wind detection of GRB 250309B
  30. IPN triangulation of GRB 250309B
  31. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  32. GRB 250309B / AT2025dws: OSIRIS+/GTC spectroscopy z=1.898
  33. GRB 250309B / AT2025dws: SAO RAS optical observations
  34. GRB 250309B / AT2025dws: Swift-UVOT detection
  35. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  36. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  37. Fermi-LAT gamma-ray observations of IceCube-250309A
  38. EP250308a: GSP optical upper limit
  39. GRB 250306A: EIRSAT-1 GMOD detection
  40. Konus-Wind detection of GRB 250306A
  41. GRB 250306A: Swift-BAT refined analysis
  42. GRB 250305A: AstroSat CZTI detection
  43. EP250302a:Xinglong optical observations
  44. GRB 250306A: AstroSat CZTI detection
  45. Fermi trigger No 762963055: Global MASTER-Net observations report
  46. LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume
  47. GRB 250306A: Swift detection of a burst
  48. EP250304A: Upper limits from Fermi-GBM Observations
  49. Fermi-LAT Gamma-ray Observations of IceCube-250302A
  50. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  51. EP 250304A: Optical counterpart detection by LCO
  52. Konus-Wind detection of GRB 250222A
  53. EP250304a: REM NIR upper limits
  54. IPN triangulation of GRB 250222A
  55. EP250304a: TRT optical counterpart detection
  56. LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate
  57. The EP-WXT trigger 01709132212 is not a real source
  58. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  59. EP250302a: SAO RAS optical observations
  60. EP250302a: Kinder optical follow-up observations
  61. LIGO/Virgo/KAGRA S250302av: 2 counterpart neutrino candidate events from an IceCube neutrino search
  62. EP250302a: NUTTelA-TAO Early Measurments
  63. EP250302a: REM NIR upper limits
  64. EP250302a: OHP/T193 optical and spectroscopic observations
  65. EP250302a: Xinglong F60B optical observation
  66. GRB 250226A: GRANDMA Optical Observations
  67. EP250302a: Montarrenti Observatory optical detection
  68. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  69. EP250228a: Optical observations with Kinder and Swift/UVOT
  70. Konus-Wind detection of GRB 250226A
  71. GRB 250225B: EIRSAT-1 GMOD Detection
  72. GRB 250226A: KAO Optical Upper Limit
  73. EP250223A: Upper limits from Fermi-GBM Observations
  74. EP250227a: TRT optical upper limit
  75. GRB 250225B: VLT/HAWKI near-infrared observations
  76. EP250227a: Optical upper limits with Kinder observations
  77. EP250227a: NOT optical observations
  78. GRB 250226A / EP250226a: LCO detection of the afterglow
  79. GRB 250205A / EP250205A: further radio observations with the VLA
  80. EP250225a: NOT optical candidate counterpart
  81. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  82. EP250225a: TRT optical upper limits
  83. EP250226a/GRB 250226A: 1.6m Mephisto observations
  84. EP250226a/GRB 250226A: Kinder optical follow-up observations
  85. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
  86. GRB 250225B: Fermi GBM Observation
  87. GRB 250221A: ATCA Detections and Upper Limits
  88. GRB 250225B: REM NIR upper limits
  89. Konus-Wind detection of GRB 250225B
  90. GRB 250214A: SVOM/GRM observation
  91. EP250226a/GRB 250226A: GSP detects optical counterpart
  92. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  93. EP250226a / GRB 250226A: TRT optical counterpart observation
  94. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  95. Swift GRB 250225B: Global MASTER-Net observations report
  96. EP250225a: GSP optical upper limit
  97. EP250223a: GMG Optical Observation
  98. GRB 250225B: Swift detection of a burst
  99. GRB 250221A: Swift-BAT refined analysis
  100. EP250223a: Kinder optical follow-up observations

Advanced

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