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"

20359 results found.

  1. GRB 251128A: GECAM-B detection
  2. GRB 251128A: SVOM/GRM observation of a long burst
  3. SVOM GRB 251129A : MASTER optical counterpart detection
  4. GRB 251129A: Swift-XRT afterglow detection
  5. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  6. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  7. GRB 251129A: SVOM detection of a burst
  8. GRB 251129A: SVOM detection of a burst
  9. GRB 251126A: Swift-BAT refined analysis
  10. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  11. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  12. GRB 251126A: further SAO RAS optical observations
  13. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  14. GRB251126A: MAO/AZT-22 optical observations
  15. GRB251126A: Continued optical observation from 1.3m DFOT
  16. GRB 251126A: Swift/UVOT Detection
  17. EP251124a: Pan-STARRS ri-band imaging and photometry
  18. GRB 251126A: Mondy and SAO RAS optical observations
  19. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  20. GRB 251126A: 1.3m DFOT optical afterglow detection
  21. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  22. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  23. GRB 251126A: Enhanced Swift-XRT position
  24. GRB 251126A: Kilonova-Catcher optical afterglow detection
  25. GRB 251126A: Nanshan/HMT optical afterglow detection
  26. GRB 251126A: GIT discovery of the likely optical afterglow
  27. GRB 251126A: Swift detection of a burst
  28. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  29. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  30. EP251124b: NOT r- and z-band optical upper limits
  31. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  32. EP251124b: EP-WXT detection of a fast X-ray transient
  33. EP251124a: Xinglong GWAC-F60A optical observation
  34. EP251124a: NOT r- and z-band optical upper limits
  35. EP251124a: Swift-XRT observations
  36. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  37. EP251124a: Optical upper limit with Kinder observations
  38. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  39. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  40. EP251124a: GROWTH-India Telescope optical upper limits
  41. EP251124a: Einstein Probe detection of an X-ray transient
  42. GRB 251116C: Swift-XRT confirmation of fading
  43. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  44. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  45. EP251118A: 3.6m DOT optical afterglow detection
  46. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  47. GRB 251122A / EP251122a: WFST optical observations
  48. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  49. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  50. GRB 251122A / EP251122a: LCO optical upper limits
  51. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  52. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  53. GRB 251122A / EP251122a: SVOM detection of a long burst
  54. EP251122a: Einstein Probe detection of an X-ray transient
  55. EP251118a: Continued Optical Detection with Kinder observations
  56. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  57. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  58. EP251118a: Xinglong-2.16m optical observation
  59. EP251118A: 1.3m DFOT optical afterglow detection
  60. GRB 251118A: Swift/UVOT Detection
  61. EP251118a / GRB 251118C: SAO RAS optical observations
  62. GRB 251118A: Swift-XRT afterglow detection
  63. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  64. EP251118a: Optical detection with Kinder observations
  65. LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results
  66. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  67. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  68. EP251118A / GRB 251118C : MASTER optical counterpart observations
  69. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  70. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  71. EP251118a: VLT near-infrared observation
  72. GRB 251116D: SVOM/GRM observation of a long GRB
  73. GRB 251119A: SVOM detection of a possible burst
  74. EP251118a: NOT spectroscopic redshift of z = 1.216
  75. EP251118a: NOT candidate optical counterpart
  76. EP251118a: Einstein Probe detected of a fast X-ray transient
  77. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  78. GRB 251116C: SVOM/ECLAIRs refined analysis
  79. GRB 251116B: SVOM/ECLAIRs refined analysis
  80. GRB 251115A: Swift-XRT observations
  81. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  82. GRB 251117A: SVOM/GRM observation of a short burst
  83. GRB 251117A: Fermi-LAT detection
  84. LIGO/Virgo/KAGRA S251117dq: Identification of a GW compact binary merger candidate
  85. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  86. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  87. EP251023a: Assy AZT-20 optical observations
  88. EP251023a: UAFO and AbAO optical observations
  89. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  90. GRB 251025B: further Mondy optical observations
  91. GRB 251111A: Mondy optical upper limit
  92. LIGO/Virgo/KAGRA S251116en: Identification of a GW compact binary merger candidate
  93. LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory
  94. GRB 251116B: LCO optical upper limits
  95. GRB 251116C: LCO optical upper limits
  96. IceCube-Cascade 251112A: Upper limits from a search for additional neutrino events in IceCube
  97. LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
  98. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  99. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 4-Update Localization Volume
  100. LIGO/Virgo/KAGRA S251112cm: DECam GW-MMADS candidates

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