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"

45477 results found.

  1. GRB 250306A: NuSTAR detection of the prompt emission
  2. EP250304a: MeerKAT detection of a possible radio counterpart
  3. IceCube-241016A: MASTER flaring blazar 5BZU J073038.29-320820.2 with Zhirkov effect
  4. GRB 250305A: AstroSat CZTI detection
  5. EP250302a:Xinglong optical observations
  6. GRB 250306A: AstroSat CZTI detection
  7. Fermi trigger No 762963055: Global MASTER-Net observations report
  8. Fermi Gamma-ray Burst Monitor trigger 762963055/250306591 is not a GRB
  9. Swift GRB 250306A: Global MASTER-Net observations report
  10. LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume
  11. GRB 250306A: Swift detection of a burst
  12. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  13. GRB250101A: Radio upper limits from VLA observations
  14. LIGO/Virgo/KAGRA S250306ej: Retraction of GW compact binary merger candidate
  15. GRB 250305A: SVOM/GRM observation of a burst
  16. The EP-WXT trigger 01709132323 is likely a flaring star
  17. EP250304A: Upper limits from Fermi-GBM Observations
  18. Fermi GRB 250305A: Global MASTER-Net observations report
  19. Fermi-LAT Gamma-ray Observations of IceCube-250302A
  20. GRB 250305A: Fermi GBM Final Real-time Localization
  21. EP250302a: Optical Observations at CrAO and SAO RAS
  22. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  23. EP 250304A: Optical counterpart detection by LCO
  24. EP250302A: 1.3m DFOT optical afterglow detection
  25. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  26. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  27. Konus-Wind detection of GRB 250222A
  28. EP250304a: REM NIR upper limits
  29. IPN triangulation of GRB 250222A
  30. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  31. EP250302a: Mondy Continued Optical Observations
  32. EP250304a: VLT/X-shooter redshift z = 0.200
  33. EP250304a: Swift-XRT detection of a fading X-ray source
  34. EP250304a: TRT optical counterpart detection
  35. LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate
  36. EP250304a: Global MASTER-Net observations report
  37. EP250304a: Einstein Probe detection of an X-ray transient
  38. The EP-WXT trigger 01709132212 is not a real source
  39. EP250302a: SVOM/VT optical observation
  40. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  41. EP250302a: SAO RAS optical observations
  42. EP250302a : GIT optical follow-up
  43. EP250302a: VLT/X-shooter redshift confirmation
  44. EP250225a: the candidate optical counterpart is an AGN
  45. EP250302a: Kinder optical follow-up observations
  46. LIGO/Virgo/KAGRA S250302av: 2 counterpart neutrino candidate events from an IceCube neutrino search
  47. EP250302a: Swift/UVOT detection
  48. EP250302a: NUTTelA-TAO Early Measurments
  49. EP250302a: optical observation from the INAF Asiago Observatory
  50. EP250302a: REM NIR upper limits
  51. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  52. EP250302a: Mondy Observations and Optical Light Curve
  53. EP250302a: VLT/MUSE optical redshift z = 1.131
  54. INTEGRAL: end of scientific operations
  55. EP250302A: VLT near-infrared observations
  56. EP250302A: VLT/X-shooter tentative redshift
  57. EP250302a: OHP/T193 optical and spectroscopic observations
  58. EP250302a: Global MASTER-Net observations report
  59. EP250302a: Xinglong F60B optical observation
  60. EP250302a: Swift-XRT observations of a fading X-ray source
  61. EP250302a: Einstein Probe detection of an X-ray transient
  62. EP250302a: SVOM/C-GFT optical observations
  63. GRB 250226A: GRANDMA Optical Observations
  64. EP250302a: Montarrenti Observatory optical detection
  65. Fermi GRB 250302A: Global MASTER-Net observations report
  66. EP250302a: FTW optical and NIR detection
  67. EP250302a: Nanshan/HMT optical counterpart detection
  68. IceCube-250302A - IceCube observation of a high-energy neutrino candidate track-like event
  69. GRB 250302A: Fermi GBM Final Real-time Localization
  70. GRB 250228A: Fermi GBM Final Localization
  71. The EP-WXT trigger 01709132140 is likely a flaring star
  72. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  73. GRB 250225B: VLT near-infrared afterglow confirmation
  74. EP250228a: Optical observations with Kinder and Swift/UVOT
  75. Konus-Wind detection of GRB 250226A
  76. GRB 250225B: EIRSAT-1 GMOD Detection
  77. GRB 250226A: KAO Optical Upper Limit
  78. GRB 250226A: AbAO AS-32 Optical Upper Limit
  79. EP250227a: Global MASTER-Net observations report
  80. EP250223A: Upper limits from Fermi-GBM Observations
  81. EP250227a: TRT optical upper limit
  82. GRB 250225B: VLT/HAWKI near-infrared observations
  83. EP250227a: Optical upper limits with Kinder observations
  84. EP250227a: NOT optical observations
  85. EP250227a: Einstein Probe detected of a fast X-ray transient
  86. EP250228a: updates on the EP observations
  87. GRB 250226A: Fermi GBM Observation
  88. EP250225a: EP-FXT follow-up observation
  89. EP250223a: J band upper limit by SYSU 80cm telescope
  90. EP250228a: Swift/XRT localisation
  91. EP250228a: Global MASTER-Net observations report
  92. EP250228a: Einstein Probe detection of an X-ray transient
  93. GRB 250226A / EP250226a: LCO detection of the afterglow
  94. LIGO/Virgo/KAGRA S250227e: Updated Sky localization
  95. LIGO/Virgo/KAGRA S250226dl: Updated Sky localization
  96. GRB 250225B: VLT/Xshooter imaging
  97. GRB 250205A / EP250205A: further radio observations with the VLA
  98. GRB 250226B: INTEGRAL SPI-ACS and PICsIT detection
  99. EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection
  100. GRB 250225B: INTEGRAL SPI-ACS detection

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