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"

45483 results found.

  1. GRB 250306A: EIRSAT-1 GMOD detection
  2. The EP-WXT trigger 01709132387 is likely a flaring star
  3. Fermi GRB 250307A: Global MASTER-Net observations report
  4. Konus-Wind detection of GRB 250306A
  5. GRB 250307A: Fermi GBM Final Real-time Localization
  6. GRB 250306A: Swift-BAT refined analysis
  7. GRB 250306A: NuSTAR detection of the prompt emission
  8. EP250304a: MeerKAT detection of a possible radio counterpart
  9. IceCube-241016A: MASTER flaring blazar 5BZU J073038.29-320820.2 with Zhirkov effect
  10. GRB 250305A: AstroSat CZTI detection
  11. EP250302a:Xinglong optical observations
  12. GRB 250306A: AstroSat CZTI detection
  13. Fermi trigger No 762963055: Global MASTER-Net observations report
  14. Fermi Gamma-ray Burst Monitor trigger 762963055/250306591 is not a GRB
  15. Swift GRB 250306A: Global MASTER-Net observations report
  16. LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume
  17. GRB 250306A: Swift detection of a burst
  18. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  19. GRB250101A: Radio upper limits from VLA observations
  20. LIGO/Virgo/KAGRA S250306ej: Retraction of GW compact binary merger candidate
  21. GRB 250305A: SVOM/GRM observation of a burst
  22. The EP-WXT trigger 01709132323 is likely a flaring star
  23. EP250304A: Upper limits from Fermi-GBM Observations
  24. Fermi GRB 250305A: Global MASTER-Net observations report
  25. Fermi-LAT Gamma-ray Observations of IceCube-250302A
  26. GRB 250305A: Fermi GBM Final Real-time Localization
  27. EP250302a: Optical Observations at CrAO and SAO RAS
  28. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  29. EP 250304A: Optical counterpart detection by LCO
  30. EP250302A: 1.3m DFOT optical afterglow detection
  31. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  32. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  33. Konus-Wind detection of GRB 250222A
  34. EP250304a: REM NIR upper limits
  35. IPN triangulation of GRB 250222A
  36. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  37. EP250302a: Mondy Continued Optical Observations
  38. EP250304a: VLT/X-shooter redshift z = 0.200
  39. EP250304a: Swift-XRT detection of a fading X-ray source
  40. EP250304a: TRT optical counterpart detection
  41. LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate
  42. EP250304a: Global MASTER-Net observations report
  43. EP250304a: Einstein Probe detection of an X-ray transient
  44. The EP-WXT trigger 01709132212 is not a real source
  45. EP250302a: SVOM/VT optical observation
  46. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  47. EP250302a: SAO RAS optical observations
  48. EP250302a : GIT optical follow-up
  49. EP250302a: VLT/X-shooter redshift confirmation
  50. EP250225a: the candidate optical counterpart is an AGN
  51. EP250302a: Kinder optical follow-up observations
  52. LIGO/Virgo/KAGRA S250302av: 2 counterpart neutrino candidate events from an IceCube neutrino search
  53. EP250302a: Swift/UVOT detection
  54. EP250302a: NUTTelA-TAO Early Measurments
  55. EP250302a: optical observation from the INAF Asiago Observatory
  56. EP250302a: REM NIR upper limits
  57. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  58. EP250302a: Mondy Observations and Optical Light Curve
  59. EP250302a: VLT/MUSE optical redshift z = 1.131
  60. INTEGRAL: end of scientific operations
  61. EP250302A: VLT near-infrared observations
  62. EP250302A: VLT/X-shooter tentative redshift
  63. EP250302a: OHP/T193 optical and spectroscopic observations
  64. EP250302a: Global MASTER-Net observations report
  65. EP250302a: Xinglong F60B optical observation
  66. EP250302a: Swift-XRT observations of a fading X-ray source
  67. EP250302a: Einstein Probe detection of an X-ray transient
  68. EP250302a: SVOM/C-GFT optical observations
  69. GRB 250226A: GRANDMA Optical Observations
  70. EP250302a: Montarrenti Observatory optical detection
  71. Fermi GRB 250302A: Global MASTER-Net observations report
  72. EP250302a: FTW optical and NIR detection
  73. EP250302a: Nanshan/HMT optical counterpart detection
  74. IceCube-250302A - IceCube observation of a high-energy neutrino candidate track-like event
  75. GRB 250302A: Fermi GBM Final Real-time Localization
  76. GRB 250228A: Fermi GBM Final Localization
  77. The EP-WXT trigger 01709132140 is likely a flaring star
  78. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  79. GRB 250225B: VLT near-infrared afterglow confirmation
  80. EP250228a: Optical observations with Kinder and Swift/UVOT
  81. Konus-Wind detection of GRB 250226A
  82. GRB 250225B: EIRSAT-1 GMOD Detection
  83. GRB 250226A: KAO Optical Upper Limit
  84. GRB 250226A: AbAO AS-32 Optical Upper Limit
  85. EP250227a: Global MASTER-Net observations report
  86. EP250223A: Upper limits from Fermi-GBM Observations
  87. EP250227a: TRT optical upper limit
  88. GRB 250225B: VLT/HAWKI near-infrared observations
  89. EP250227a: Optical upper limits with Kinder observations
  90. EP250227a: NOT optical observations
  91. EP250227a: Einstein Probe detected of a fast X-ray transient
  92. EP250228a: updates on the EP observations
  93. GRB 250226A: Fermi GBM Observation
  94. EP250225a: EP-FXT follow-up observation
  95. EP250223a: J band upper limit by SYSU 80cm telescope
  96. EP250228a: Swift/XRT localisation
  97. EP250228a: Global MASTER-Net observations report
  98. EP250228a: Einstein Probe detection of an X-ray transient
  99. GRB 250226A / EP250226a: LCO detection of the afterglow
  100. LIGO/Virgo/KAGRA S250227e: Updated Sky localization

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