Skip to main content
JSON Notices via Email, Kafka Cron Jobs, Submitter Profile, GCN is Hiring. See news and announcements

GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

28126 results found.

  1. GRB 250306A: Swift-BAT refined analysis
  2. GRB 250306A: NuSTAR detection of the prompt emission
  3. EP250304a: MeerKAT detection of a possible radio counterpart
  4. IceCube-241016A: MASTER flaring blazar 5BZU J073038.29-320820.2 with Zhirkov effect
  5. GRB 250305A: AstroSat CZTI detection
  6. EP250302a:Xinglong optical observations
  7. LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume
  8. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  9. GRB250101A: Radio upper limits from VLA observations
  10. GRB 250305A: SVOM/GRM observation of a burst
  11. The EP-WXT trigger 01709132323 is likely a flaring star
  12. EP250304A: Upper limits from Fermi-GBM Observations
  13. Fermi-LAT Gamma-ray Observations of IceCube-250302A
  14. EP250302a: Optical Observations at CrAO and SAO RAS
  15. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  16. EP 250304A: Optical counterpart detection by LCO
  17. EP250302A: 1.3m DFOT optical afterglow detection
  18. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  19. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  20. EP250304a: REM NIR upper limits
  21. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  22. EP250302a: Mondy Continued Optical Observations
  23. EP250304a: Swift-XRT detection of a fading X-ray source
  24. EP250304a: TRT optical counterpart detection
  25. LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate
  26. EP250304a: Einstein Probe detection of an X-ray transient
  27. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  28. EP250302a: SAO RAS optical observations
  29. EP250302a : GIT optical follow-up
  30. EP250225a: the candidate optical counterpart is an AGN
  31. EP250302a: Kinder optical follow-up observations
  32. LIGO/Virgo/KAGRA S250302av: 2 counterpart neutrino candidate events from an IceCube neutrino search
  33. EP250302a: Swift/UVOT detection
  34. EP250302a: optical observation from the INAF Asiago Observatory
  35. EP250302a: REM NIR upper limits
  36. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  37. EP250302a: Mondy Observations and Optical Light Curve
  38. EP250302a: VLT/MUSE optical redshift z = 1.131
  39. EP250302A: VLT near-infrared observations
  40. EP250302A: VLT/X-shooter tentative redshift
  41. EP250302a: OHP/T193 optical and spectroscopic observations
  42. EP250302a: Swift-XRT observations of a fading X-ray source
  43. EP250302a: Einstein Probe detection of an X-ray transient
  44. EP250302a: SVOM/C-GFT optical observations
  45. GRB 250226A: GRANDMA Optical Observations
  46. EP250302a: Montarrenti Observatory optical detection
  47. EP250302a: Nanshan/HMT optical counterpart detection
  48. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  49. GRB 250225B: VLT near-infrared afterglow confirmation
  50. EP250228a: Optical observations with Kinder and Swift/UVOT
  51. Konus-Wind detection of GRB 250226A
  52. GRB 250225B: EIRSAT-1 GMOD Detection
  53. GRB 250226A: KAO Optical Upper Limit
  54. GRB 250226A: AbAO AS-32 Optical Upper Limit
  55. EP250227a: Global MASTER-Net observations report
  56. EP250223A: Upper limits from Fermi-GBM Observations
  57. EP250227a: TRT optical upper limit
  58. GRB 250225B: VLT/HAWKI near-infrared observations
  59. EP250227a: Optical upper limits with Kinder observations
  60. EP250227a: NOT optical observations
  61. EP250227a: Einstein Probe detected of a fast X-ray transient
  62. EP250228a: updates on the EP observations
  63. GRB 250226A: Fermi GBM Observation
  64. EP250223a: J band upper limit by SYSU 80cm telescope
  65. EP250228a: Swift/XRT localisation
  66. EP250228a: Einstein Probe detection of an X-ray transient
  67. GRB 250226A / EP250226a: LCO detection of the afterglow
  68. LIGO/Virgo/KAGRA S250227e: Updated Sky localization
  69. LIGO/Virgo/KAGRA S250226dl: Updated Sky localization
  70. GRB 250225B: VLT/Xshooter imaging
  71. GRB 250205A / EP250205A: further radio observations with the VLA
  72. EP250225a: NOT optical candidate counterpart
  73. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  74. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  75. EP250225a: TRT optical upper limits
  76. EP250226a/GRB 250226A: 1.6m Mephisto observations
  77. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  78. EP250226a/GRB 250226A: Kinder optical follow-up observations
  79. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  80. LIGO/Virgo/KAGRA S250227e: Identification of a GW compact binary merger candidate
  81. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
  82. GRB 250225B: Fermi GBM Observation
  83. GRB 250225B: REM NIR upper limits
  84. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  85. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  86. EP250223a: CrAO ZTSH optical observation
  87. GRB 250225B: VLT optical and near-infrared candidate counterpart
  88. GRB 250225B: SVOM/GRM observation of a long burst
  89. EP250226a/GRB 250226A: GSP detects optical counterpart
  90. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  91. EP250226a / GRB 250226A: TRT optical counterpart observation
  92. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  93. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  94. EP250225a: GSP optical upper limit
  95. EP250223a: GMG Optical Observation
  96. EP250225a: Einstein Probe detected of a fast X-ray transient
  97. GRB 250225B: Swift detection of a burst
  98. EP250223a: GROWTH-India Telescope optical observations
  99. GRB 250221A: Swift-BAT refined analysis
  100. EP250215A: J band upper limit by SYSU 80cm telescope

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