Skip to main content
New! Super-Kamiokande JSON Notices and Schema v4.5.0. 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"

26129 results found.

  1. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  2. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  3. EP251118A: 3.6m DOT optical afterglow detection
  4. GRB 251122A / EP251122a: EP-FXT counterpart detection
  5. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  6. GRB 251122A / EP251122a: WFST optical observations
  7. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  8. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  9. GRB 251122A / EP251122a: LCO optical upper limits
  10. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  11. EP251122a: Global MASTER-Net observations report
  12. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  13. GRB 251122A / EP251122a: SVOM detection of a long burst
  14. EP251122a: Einstein Probe detection of an X-ray transient
  15. EP251118a: Continued Optical Detection with Kinder observations
  16. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  17. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  18. GRB 251121A: Glowbug gamma-ray detection of a likely short burst
  19. EP251118a: Xinglong-2.16m optical observation
  20. GRB 251115A: Fermi GBM Observation
  21. Fermi trigger No 785388351: Global MASTER-Net observations report
  22. EP251118A: 1.3m DFOT optical afterglow detection
  23. GRB 251118A: Swift/UVOT Detection
  24. EP251118a / GRB 251118C: SAO RAS optical observations
  25. GRB 251118A: Glowbug gamma-ray detection
  26. GRB 251118A: Fermi GBM Observation
  27. GRB 251118A: Swift-XRT afterglow detection
  28. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  29. EP251118a: Optical detection with Kinder observations
  30. LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results
  31. GRB 251118A: NuSTAR detection of bright prompt emission
  32. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  33. GRB 251116C: NOT optical observations
  34. GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A
  35. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  36. GRB 251117A: Swift-XRT observations
  37. EP251118A / GRB 251118C : MASTER optical counterpart observations
  38. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  39. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  40. EP251118a: VLT near-infrared observation
  41. GRB 251116D: SVOM/GRM observation of a long GRB
  42. GRB 251119A: SVOM detection of a possible burst
  43. EP251118a: Global MASTER-Net observations report
  44. LAT GRB251118.86: Global MASTER-Net observations report
  45. EP251118a: NOT candidate optical counterpart
  46. EP251118a: Einstein Probe detected of a fast X-ray transient
  47. Fermi GRB 251118B: Global MASTER-Net observations report
  48. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  49. GRB 251118A: BALROG localization (Fermi Trigger 785190695 / GRB 251118855)
  50. GRB 251117A: AstroSat CZTI detection
  51. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  52. LIGO/Virgo/KAGRA S251117dq: Updated Sky localization
  53. GRB 251115A: Swift-XRT observations
  54. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  55. GRB 251117A: SVOM/GRM observation of a short burst
  56. LAT GRB251117.51: Global MASTER-Net observations report
  57. LIGO/Virgo/KAGRA S251117dq: Identification of a GW compact binary merger candidate
  58. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  59. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  60. GRB 251116C: Swift-XRT observations
  61. LIGO/Virgo/KAGRA S251116en: Updated Sky localization
  62. GRB 251116D: Glowbug gamma-ray detection
  63. EP251023a: Assy AZT-20 optical observations
  64. EP251023a: UAFO and AbAO optical observations
  65. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  66. GRB 251116C: SVOM/VT optical upper limit
  67. GRB 251025B: further Mondy optical observations
  68. GRB 251111A: Mondy optical upper limit
  69. GRB 251116B: EP-FXT follow-up observation
  70. LIGO/Virgo/KAGRA S251116en: Identification of a GW compact binary merger candidate
  71. LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory
  72. GRB 251116B: LCO optical upper limits
  73. GRB 251116C: LCO optical upper limits
  74. SVOM GRB251116C: Global MASTER-Net observations report
  75. GRB 251116B: SVOM detection of a burst
  76. IceCube-Cascade 251112A: Upper limits from a search for additional neutrino events in IceCube
  77. LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
  78. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  79. Fermi GRB 251115A: Global MASTER-Net observations report
  80. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 4-Update Localization Volume
  81. LIGO/Virgo/KAGRA S251112cm: DECam GW-MMADS candidates
  82. LIGO/Virgo/KAGRA S251112cm: Updated Sky localization and false alarm rate estimate
  83. GRB 251113A: Glowbug gamma-ray detection
  84. GRB 251112A: Swift-BAT refined analysis
  85. Fermi trigger No 784717756: Global MASTER-Net observations report
  86. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  87. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  88. Fermi GRB 251114A: Global MASTER-Net observations report
  89. LIGO/Virgo/KAGRA S251112cm: FTW observations of galaxies within localization region
  90. Fermi GRB 251113A: Global MASTER-Net observations report
  91. GRB 251113A: BALROG localization (Fermi Trigger 784748255 / GRB 251113734)
  92. GRB 251112A: Swift/UVOT Upper Limits
  93. LIGO/Virgo/KAGRA S251112cm: ATLAS pre-detections of AT2025adgp and AT2025adgq
  94. GRB 251112A: Swift-XRT refined Analysis
  95. GRB 251112B: MAXI/GSC detection
  96. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  97. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  98. GRB 251108B: Glowbug gamma-ray detection
  99. Swift Trigger 1413695: a possible GRB 251112A
  100. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations

Advanced

Download all Circulars as a .tar.gz archive:
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