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"

23594 results found.

  1. GRB 250128B: Swift detection of a short burst
  2. GRB 250127A: Swift-XRT observations
  3. GRB 250127B: DDOTI Upper Limit on the Afterglow
  4. Fermi GRB 250128A: Global MASTER-Net observations report
  5. GRB 250127A: SVOM/VT upper limit
  6. IPN triangulation of GRB 250119C
  7. GRB 250127A: LCO optical upper limit
  8. GRB 241223A: cubesat Avion detection
  9. EP250125a: Optical upper limit with Kinder observations
  10. EP250125a: REM optical counterpart detection
  11. EP250125a: Swift/XRT detection of a fading counterpart
  12. EP250125a: a new X-ray transient detected by Einstein Probe
  13. EP250125a: Gemini-South optical afterglow discovery and redshift z = 2.89
  14. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  15. EP250108a: AbAO, CMO and Terskol optical upper limits
  16. Konus-Wind detection of GRB 250118B
  17. IPN triangulation of GRB 250118B
  18. Konus-Wind detection of GRB 250119B
  19. IPN triangulation of GRB 250119B
  20. Improved IPN triangulation of GRB 250107C
  21. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  22. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  23. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  24. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  25. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  26. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  27. Konus-Wind detection of GRB 250117A
  28. IPN triangulation of GRB 250117A (short)
  29. LIGO/Virgo/KAGRA S250119cv: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  30. EP 250108A: Late-time optical observation by LCO
  31. LIGO/Virgo/KAGRA S250105bn: 1 counterpart neutrino candidate event from an IceCube neutrino search
  32. LIGO/Virgo/KAGRA S250119cv: Updated Sky localization and EM Bright Classification
  33. LIGO/Virgo/KAGRA S250119cv: NED Galaxies in the Localization Volume
  34. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  35. LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
  36. LIGO/Virgo/KAGRA S250119ag: Identification of a GW compact binary merger candidate
  37. LIGO/Virgo/KAGRA S250118dp: Identification of a GW compact binary merger candidate
  38. LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
  39. EP250108a / AT2025kg: GMG Optical Observations
  40. LIGO/Virgo/KAGRA S250118t: Identification of a GW compact binary merger candidate
  41. EP250108a / AT2025kg: VLA radio upper limit
  42. Konus-Wind detection of GRB 250116A
  43. GRB 241217A / EP241217B: radio detection with the VLA
  44. GRB 250114B: Swift-XRT afterglow detection
  45. GRB 250114B: SVOM/VT upper limit
  46. EP250108a: MeerKAT radio upper limit
  47. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  48. IPN triangulation of GRB 250113A
  49. GRB 250114B: Liverpool Telescope optical upper limit
  50. LIGO/Virgo/KAGRA S250114ax: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  51. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  52. GRB 250114B: Swift-XRT observations
  53. GRB 250114A: LCO optical counterpart detection.
  54. GRB 250114B: OHP/T193 optical upper limit
  55. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  56. GRB 250114A: Swift-XRT refined Analysis
  57. GRB 250114A: LCOGT optical afterglow i-band detection
  58. GRB 250114B : GIT optical upper limit
  59. EP250111a: SAO RAS optical upper limit
  60. LIGO/Virgo/KAGRA S250114ax: NED Galaxies in the Localization Volume
  61. GRB 250114A: Enhanced Swift-XRT position
  62. GRB 250113A: INTEGRAL/SPI-ACS detection
  63. GRB 250114A: REM detection of the optical and NIR counterpart
  64. LIGO/Virgo/KAGRA S250114ax: Identification of a GW compact binary merger candidate
  65. GRB 250114A: LCO optical observations
  66. GRB 250114A: TRT optical observations
  67. GRB 250114A: Swift detection of a burst with an optical counterpart
  68. GRB 250101A: Terskol Zeiss-2000 optical observations
  69. EP250108a / AT 2025kg: SAO RAS optical observations
  70. EP241021a: SMA radio observation
  71. GRB 250113A: SVOM/GRM observation of a long burst
  72. EP250109b: optical upper limits with the Liverpool Telescope
  73. GRB 250106A: Swift-XRT afterglow detection
  74. EP250111a: KAIT optical observations
  75. GRB 250109A / EP250109a: Mephisto optical upper limits
  76. EP250108a: Mephisto detection
  77. EP250111a: Mondy optical observation
  78. EP250108a / AT 2025kg: LCO optical observations
  79. EP250108a / AT 2025kg: Swift UVOT detections
  80. EP250111a: NOT likely optical counterpart
  81. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  82. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  83. EP-WXT trigger EP250108a：Xinglong optical follow-up observations
  84. GRB 250101A: CMO RC-500 optical observations
  85. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  86. EP250108a: EP-FXT follow-up observation
  87. EP250108a: NOT optical observations
  88. EP-WXT trigger EP250109a：Xinglong optical follow-up observations
  89. GRB 250109a: GMG Optical Upper Limit
  90. EP250109a: Swift/UVOT non-detection
  91. Konus-Wind detection of GRB 250107D (short/hard)
  92. IPN triangulation of GRB 250107D (short/hard)
  93. IPN triangulation of GRB 250107C
  94. EP250108a: Liverpool Telescope likely optical counterpart
  95. GRB 250108B: 1.3m DFOT upper limit
  96. GRB 250108B: REM optical/NIR upper limits
  97. EP250109a: SVOM/VT optical candidate
  98. GRB 250101A: Terskol K-800 optical observations
  99. EP250109a: GOTO optical upper limits
  100. EP250109a: Swift/XRT non-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