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"

28301 results found.

  1. GRB 250904A: Swift detection of a burst
  2. LIGO/Virgo/KAGRA S250904ae: Updated Sky localization
  3. GRB 250902A: VZLUSAT-2 detection
  4. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  5. GRB 250903A: Swift-XRT observations
  6. EP250903a: Swift-XRT observations
  7. EP#01709201209: Swift-XRT observations
  8. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  9. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  10. GRB 250830C: VZLUSAT-2 detection
  11. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  12. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  13. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  14. GRB 250903A: EP-FXT counterpart detection
  15. GRB 250902A: GECAM-B detection
  16. GRB 250903A: LCO optical observation
  17. GRB 250903A: LCO optical afterglow detection
  18. GRB 250903A: SVOM/VT optical confirmation with VHF data
  19. EP250901a: Mondy, Assy and SAO RAS optical limits
  20. EP250903a: LCO candidate counterpart discovery
  21. GRB 250903A: TRT optical counterpart detection
  22. EP250903a: TRT optical observations
  23. EP250903a: Einstein Probe detection of an X-ray transient
  24. EP 250827B: Detection of supernova counterpart by LCO.
  25. GRB 250902B: SVOM/GRM observation
  26. EP250827b: SVOM/VT observation of AT 2025wkm
  27. LIGO/VIRGO/KAGRA S250818k: No evidence for radio variability of AT2025ulz in MeerKAT 3 GHz data
  28. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  29. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  30. GRB 250902A: Fermi GBM Detection
  31. GRB 250901A: Swift/UVOT Upper Limit
  32. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  33. GRB 250830B: Swift-XRT afterglow detection
  34. LIGO/Virgo/KAGRA S250902av: 1 counterpart neutrino candidate event from an IceCube neutrino search
  35. LIGO/Virgo/KAGRA S250901cb: Updated Sky localization
  36. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  37. GRB 250902A: SVOM/GRM observation
  38. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  39. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  40. IceCube-Cascade 250828A: Upper limits from a search for additional neutrino events in IceCube
  41. GRB 250901A: SVOM/VT optical afterglow with VHF data
  42. GRB 250901A: Swift-XRT afterglow detection
  43. EP250901a: Swift-XRT observations
  44. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  45. GRB 250901A: LCO optical upper limit
  46. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 1 Candidates
  47. EP250827b: Gemini Spectroscopy of AT 2025wkm
  48. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  49. EP250831a: NOT optical observations and tentative afterglow candidate
  50. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  51. GRB 250901A: SVOM detection of a burst
  52. EP250901a: Mephisto optical upper limits
  53. GRB 250830C: GECAM-B detection
  54. EP250901a: Einstein Probe detection of an X-ray transient
  55. LIGO/Virgo/KAGRA S250830m: Updated Sky localization
  56. EP250831a: Swift-XRT observations
  57. LIGO/Virgo/KAGRA S250831cc: Coverage and upper limits from MAXI/GSC observations
  58. EP250831a: EP-WXT detection of a fast X-ray transient
  59. GRB 250831A: Swift-XRT counterpart detection
  60. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  61. GRB 250831A: SVOM/VT upper limit with VHF data
  62. GRB 250831A: SVOM detection of a soft burst
  63. GRB 250830B: Swift-XRT observations
  64. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  65. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations
  66. LIGO/Virgo/KAGRA S250830bp GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  67. LIGO/Virgo/KAGRA S250830bp: NED Galaxies in the 4-Update Localization Volume
  68. LIGO/Virgo/KAGRA S250830bp: Updated Sky localization, EM Bright Classification, and Source Classification
  69. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  70. EP-WXT trigger 01709200994: Liverpool Telescope upper limits
  71. EP-WXT trigger 01709200994: confirmation of a stellar flare by BOOTES-6
  72. GRB 250830B: MAXI/GSC detection
  73. LIGO/Virgo/KAGRA S250830m: Identification of a GW compact binary merger candidate
  74. GRB 250830A / MAXI J0853+337: MAXI/GSC detection
  75. GRB 250828B: Swift-BAT refined analysis
  76. LIGO/Virgo/KAGRA S250725j: Observations with the NSF-DOE Vera C. Rubin Observatory
  77. LIGO/Virgo/KAGRA S250818k: MeerKAT detection of an increase in radio flux from AT2025ulz
  78. EP250828a: refined analysis of the EP-WXT and EP-FXT observations
  79. EP250828a: Optical counterpart detection with Kinder observations
  80. EP250828a: Liverpool Telescope upper limits
  81. EP250828a: Global MASTER-Net observations report
  82. EP-WXT trigger 01709200800 : KAIT optical observations
  83. EP250828a: KAIT optical upper limit
  84. EP250827a: Swift/UVOT Detection
  85. EP250828a: NOT optical counterpart confirmation
  86. EP250828a: SVOM/VT optical candidate
  87. EP250828a: Seimei/TriCCS optical counterpart detection
  88. EP250828a: Optical upper limit with Kinder observations
  89. LIGO/Virgo/KAGRA S250827fo: Updated Sky localization
  90. EP250827a: LCO observations show fading optical counterpart
  91. EP250828a: Einstein Probe detection of an X-ray transient
  92. EP250827a: Preliminary analysis of the EP-WXT and EP-FXT observations
  93. LIGO/Virgo/KAGRA S250827fo: Identification of a GW compact binary merger candidate
  94. EP250827a: confirmation of optical rebrightening with LCO
  95. GRB 250826A: SVOM/GRM observation
  96. EP250827A: An optical rebrightening was detected by LCO.
  97. EP250827a: Swift-XRT counterpart detection
  98. LIGO/Virgo/KAGRA S250827l: Updated Sky localization
  99. EP250827a: TRT optical observations
  100. EP250827a: Gemini-South redshift z = 1.613

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