Skip to main content
End of Swift Science Operations, CHIME Notices Unavailable During Upgrade. 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"

46030 results found.

  1. GRB 250114B: Liverpool Telescope optical upper limit
  2. LIGO/Virgo/KAGRA S250114ax: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  3. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  4. GRB 250114B: Swift-XRT observations
  5. GRB 250114A: LCO optical counterpart detection.
  6. GRB 250114B: OHP/T193 optical upper limit
  7. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  8. GRB 250114A: Swift-XRT refined Analysis
  9. Integral GRB250114.55: Global MASTER-Net observations report
  10. GRB 250114A: LCOGT optical afterglow i-band detection
  11. GRB 250114B : GIT optical upper limit
  12. GRB 250114B: Swift ToO observations
  13. EP250111a: SAO RAS optical upper limit
  14. LIGO/Virgo/KAGRA S250114ax: NED Galaxies in the Localization Volume
  15. GRB 250114B: a short GRB detected with INTEGRAL
  16. EP250108a: correction to GCN 38908
  17. GRB 250114A: Enhanced Swift-XRT position
  18. GRB 250113A: INTEGRAL/SPI-ACS detection
  19. GRB 250114A: VLT/X-shooter spectroscopic redshift z = 4.732
  20. GRB 250114A: REM detection of the optical and NIR counterpart
  21. LIGO/Virgo/KAGRA S250114ax: Identification of a GW compact binary merger candidate
  22. Swift GRB250114A: Global MASTER-Net OT detection
  23. GRB 250114A: LCO optical observations
  24. GRB 250114A: TRT optical observations
  25. Swift GRB 250114A: Global MASTER-Net observations report
  26. GRB 250114A: Swift detection of a burst with an optical counterpart
  27. GRB 250101A: Terskol Zeiss-2000 optical observations
  28. EP250108a / AT 2025kg: SAO RAS optical observations
  29. EP241021a: SMA radio observation
  30. GRB 250113A: SVOM/GRM observation of a long burst
  31. GRB 250107A: VZLUSAT-2 detection
  32. EP250109b: optical upper limits with the Liverpool Telescope
  33. GRB 250109A / EP250109a: GRBAlpha detection
  34. GRB 250107D: GRBAlpha detection
  35. GRB 250106A: Swift-XRT afterglow detection
  36. Fermi trigger No 758442826: Global MASTER-Net observations report
  37. EP250111a: KAIT optical observations
  38. GRB 250109A / EP250109a: Mephisto optical upper limits
  39. EP250108a: Mephisto detection
  40. EP250111a: Mondy optical observation
  41. EP250108a / AT 2025kg: LCO optical observations
  42. EP250111a: Global MASTER-Net observations report
  43. EP250111a: Swift/XRT detection and fading
  44. EP250108a / AT 2025kg: Swift UVOT detections
  45. EP250108a / AT 2025kg (the "kangaroo”): VLT/X-shooter spectroscopic redshift z = 0.176 and LFBOT classification
  46. EP250108a: optical follow-up observations with the Liverpool Telescope
  47. EP250111a: NOT likely optical counterpart
  48. EP250111a: a new X-ray transient detected by Einstein Probe
  49. EP250109a/GRB 250109A:SVOM/VT optical counterpart
  50. GRB 250101B: Fermi GBM Observation
  51. EP250108a: further NOT optical observations
  52. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  53. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  54. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  55. GRB 250108A: Swift/XRT afterglow fading
  56. GRB 250107D: CALET Gamma-Ray Burst Monitor detection
  57. GRB 250107C: CALET Gamma-Ray Burst Monitor detection
  58. Konus-Wind detection of GRB 250107C
  59. LIGO/Virgo/KAGRA S250109bi: Updated Sky localization
  60. LIGO/Virgo/KAGRA S250109f: Updated Sky localization
  61. LIGO/Virgo/KAGRA S250108eo: Updated Sky localization
  62. EP-WXT trigger EP250108a：Xinglong optical follow-up observations
  63. GRB 250101A: CMO RC-500 optical observations
  64. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  65. EP250108a: EP-FXT follow-up observation
  66. GRB 250109A: Fermi GBM Observation
  67. The EP-WXT trigger 01709130111 is likely a flaring star
  68. EP250108a: NOT optical observations
  69. EP-WXT trigger EP250109a：Xinglong optical follow-up observations
  70. GRB 250109a: GMG Optical Upper Limit
  71. EP250109a: Swift/UVOT non-detection
  72. Konus-Wind detection of GRB 250107D (short/hard)
  73. IPN triangulation of GRB 250107D (short/hard)
  74. IPN triangulation of GRB 250107C
  75. EP250108a: Liverpool Telescope likely optical counterpart
  76. GRB 250108B: Gemini-North likely redshift z = 2.197
  77. GRB 250108B: Swift-BAT refined analysis
  78. GRB 250108B: 1.3m DFOT upper limit
  79. GRB 250108B: REM optical/NIR upper limits
  80. GRB 250109A /EP250109a: Fermi GBM Final Localization
  81. EP250109a: SVOM/VT optical candidate
  82. EP250109a: Global MASTER-Net observations report
  83. GRB 250107C: SVOM/GRM observation
  84. GRB 250101A: Terskol K-800 optical observations
  85. EP250109a: GOTO optical upper limits
  86. EP250109a: Swift/XRT non-detection
  87. GRB 250108A: Swift/UVOT Upper Limits
  88. EP250108a: Global MASTER-Net observations report
  89. EP250109a: EP-WXT detection of an X-ray transient
  90. LIGO/Virgo/KAGRA S250109bi: Identification of a GW compact binary merger candidate
  91. GRB 250108A: NOT optical upper limit
  92. EP250108a: EP-WXT detection of an X-ray transient
  93. LIGO/Virgo/KAGRA S250109f: Identification of a GW compact binary merger candidate
  94. GRB 250108B: Swift-XRT refined Analysis
  95. Swift GRB 250108B: Global MASTER-Net observations report
  96. Fermi Gamma-ray Burst Monitor trigger 758061038/250108855 is not a GRB
  97. LIGO/Virgo/KAGRA S250108ha: Retraction of GW compact binary merger candidate
  98. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  99. GRB 250103A: 1.6m Mephisto optical observations
  100. GRB 250108A: Swift-XRT afterglow 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