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"

19572 results found.

  1. GRB 250314A: Keck/NIRC2 J-band upper limit
  2. EP250226a/GRB 250226A: KAIT optical observations
  3. GRB 250321A: Swift detection of a burst
  4. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  5. GRB 250317B: Mondy AZT-33IK Continued Optical Observations
  6. GRB 250317B: SVOM/COLIBRI (F-GFT) follow-up observations
  7. GRB 250317C: SVOM/GRM observation of a long burst
  8. GRB 250317B: Leavitt Observatory optical upper limit
  9. GRB 250317B: Mondy AZT-33IK Optical Observations
  10. GRB 250317B: NOT optical observations suggest an optical plateau phase
  11. GRB 250317B: OHP/T193 optical observations
  12. GRB250312A: Swift/UVOT Upper Limits
  13. GRB 250317B: REM optical/NIR observations
  14. GRB 250316A: Swift/UVOT Upper Limits
  15. GRB 250314A: REM optical/NIR upper limits
  16. GRB 250316A: AbAO AS-32 Optical Upper Limit
  17. EP 250317B: Fading optical counterpart detection by LCO
  18. GRB 250316A: Swift-XRT afterglow detection
  19. GRB 250317B: LCO detection of the fading optical afterglow
  20. GRB 250317B: SVOM/VT detection of an optical candidate from VHF data
  21. GRB 250317B: SVOM/F-GFT (COLIBRÍ) Detection of a Fading Optical Counterpart
  22. GRB 250317B: SVOM detection of a burst / correction to GRB name of GCN 39752
  23. GRB 250317B: SVOM detection of a burst
  24. GRB 250316A: Swift ToO observations
  25. EP250315a: refined analysis of the EP-WXT and EP-FXT observations
  26. GRB 250314A: Swift/UVOT Upper Limits
  27. GRB 250314A: Swift XRT Detection
  28. EP250315a: optical counterpart candidate detected by Gemini North
  29. EP250315a: Einstein Probe detection of an X-ray transient
  30. GRB 250226A: Mondy AZT-33IK and Koshka Zeiss-1000 Optical Upper Limits
  31. SVOM/MXT upper limit on GRB 250314A
  32. GRB 250314A: SVOM/VT upper limit
  33. GRB 250314A: NOT near-infrared candidate counterpart
  34. GRB250314A: SVOM/VT lack of bright optical candidate from VHF data
  35. GRB 250314A: SVOM detection of a burst
  36. GRB 250313A: Swift ToO observations
  37. EP250304a: Pan-STARRS r and i-band imaging and photometry
  38. GRB 250312B: Swift/BAT-GUANO localization skymap of a burst
  39. GRB 250309B: PRIME near-infrared upper limits in 2nd epoch
  40. GRB 250312A: Enhanced Swift-XRT position
  41. LIGO/Virgo/KAGRA S250304cb: Upper limits from Swift/BAT-GUANO
  42. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  43. GRB 250312A: Swift detection of a burst
  44. GRB 241213A: VIRT Optical Upper Limit
  45. GRB 241228A: VIRT Optical Upper Limit
  46. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  47. GRB 250309B: 1.3m DFOT Optical observations
  48. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  49. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  50. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  51. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  52. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  53. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  54. GRB 250309B: PRIME near-infrared detection
  55. EP250304a: Chandra detection
  56. GRB 250225B: Swift-BAT refined analysis
  57. GRB 250311A/EP250311a: TRT optical upper limit
  58. GRB 250311A: Tiled Swift observations
  59. EP250311a/GRB 250311A: EP-WXT detection
  60. GRB 250308A: CALET Gamma-Ray Burst Monitor detection
  61. GRB 250311B: SVOM detection of a burst
  62. GRB 250309B / AT2025dws: further SAO RAS optical observations
  63. EP250308a: 1.6m Mephisto optical upper limits
  64. Konus-Wind detection of GRB 250309B
  65. IPN triangulation of GRB 250308A (short)
  66. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  67. GRB 250309B / AT2025dws: SAO RAS optical observations
  68. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  69. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  70. IceCube-250309A: No candidates from the Zwicky Transient Facility
  71. Fermi-LAT gamma-ray observations of IceCube-250309A
  72. GRB 230509B: Tiled Swift observations
  73. EP250308a: Einstein Probe detection of an X-ray transient
  74. EP250308a: NOT optical upper limit
  75. EP250304a: MeerKAT detection of a possible radio counterpart
  76. GRB 250305A: AstroSat CZTI detection
  77. EP250302a:Xinglong optical observations
  78. GRB 250306A: AstroSat CZTI detection
  79. GRB250101A: Radio upper limits from VLA observations
  80. GRB 250305A: SVOM/GRM observation of a burst
  81. Fermi-LAT Gamma-ray Observations of IceCube-250302A
  82. EP250302a: Optical Observations at CrAO and SAO RAS
  83. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  84. EP 250304A: Optical counterpart detection by LCO
  85. EP250302A: 1.3m DFOT optical afterglow detection
  86. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  87. EP250304a: REM NIR upper limits
  88. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  89. EP250302a: Mondy Continued Optical Observations
  90. EP250304a: TRT optical counterpart detection
  91. EP250304a: Einstein Probe detection of an X-ray transient
  92. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  93. EP250302a: SAO RAS optical observations
  94. EP250302a : GIT optical follow-up
  95. EP250302a: Kinder optical follow-up observations
  96. EP250302a: Swift/UVOT detection
  97. EP250302a: optical observation from the INAF Asiago Observatory
  98. EP250302a: REM NIR upper limits
  99. EP250302a: Mondy Observations and Optical Light Curve
  100. EP250302a: VLT/MUSE optical redshift z = 1.131

Advanced

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