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"

32752 results found.

  1. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  2. GRB 250728A: Swift ToO observations
  3. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  4. GRB 250727A: AST3-2 Upper limit
  5. LIGO/Virgo/KAGRA S250727cl: Updated Sky localization
  6. GRB 250727A: EP-FXT counterpart detection
  7. GRB250727A: SVOM/VT optical upper limit
  8. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  9. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  10. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  11. LIGO/Virgo/KAGRA S250725l: Updated Sky localization
  12. LIGO/Virgo/KAGRA S250726ak: Updated Sky localization
  13. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  14. GRB 250725A: Fermi GBM Observation
  15. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  16. GRB 250725A: Swift-BAT refined analysis
  17. Konus-Wind detection of GRB 250725A
  18. GRB 250725A: SVOM/GRM observation
  19. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  20. GRB 250725A: Swift/UVOT Upper Limits
  21. GRB 250725A: Fermi-LAT detection
  22. GRB 250725A: VLT/FORS2 spectroscopic redshift z = 5.26
  23. GRB 250725A: BOOTES-7 early optical detection
  24. GRB 250725A: SVOM/VT optical candidate
  25. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate (duplicate submission)
  26. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  27. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  28. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  29. SVOM J195836+32283 is not a real source
  30. SVOM J195836+32283/sb25072103: Second VT observation
  31. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  32. GRB 250721A: Fermi GBM Observation
  33. SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits
  34. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  35. GRB 250713A : SVOM/ECLAIRs refined analysis
  36. GRB 250717B: SVOM/GRM observation
  37. LIGO/Virgo/KAGRA S250711q: Updated Sky localization
  38. GRB 250721A: Tiled Swift observations
  39. GRB 250721A: MAXI/GSC detection
  40. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  41. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  42. GRB 250717B: COLIBRÍ optical upper limit
  43. GRB 250718B: Fermi GBM Final Localization Correction
  44. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  45. GRB 250717B: Swift ToO observations
  46. GRB 270713A: Kitab and AbAO Optical Observations
  47. GRB 250717B: Fermi GBM Observation
  48. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  49. Konus-Wind detection of GRB 250716A
  50. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  51. GRB 250716A: Swift ToO observations
  52. GRB 250714A: SVOM/GRM observation
  53. Fermi GRB 250716A: Global MASTER-Net observations report
  54. Fermi GRB 250715A: Global MASTER-Net observations report
  55. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  56. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
  57. GRB 250713A: Mephisto optical upper limits
  58. Fermi GRB 250714A: Global MASTER-Net observations report
  59. GRB 250713A: SVOM/VT optical upper limit
  60. GRB 250713A: NOT optical upper limits
  61. GRB 250713A: OHP/T193 upper limit
  62. GRB 250713A: SVOM/C-GFT upper limit
  63. GRB 250706B/C: 7DT Follow-up Observations
  64. GRB 250713A: EP-FXT counterpart detection
  65. EP250711a: COLIBRÍ continuous optical observations
  66. GRB 250706A: Swift-BAT refined analysis
  67. GRB 250702F: Swift-BAT refined analysis
  68. GRB 250628A: Swift-BAT refined analysis
  69. LIGO/Virgo/KAGRA S250712cd: Updated Sky localization
  70. GRB 250713A: JinShan optical upper limits
  71. EP250711a: Global MASTER-Net observations report
  72. GRB 250711A: DDOTI Optical Upper Limit
  73. LIGO/Virgo/KAGRA S250712cd: Identification of a GW compact binary merger candidate
  74. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate (duplicate submission)
  75. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
  76. GRB 250711A: SVOM/GRM observation
  77. EP250711a: NOT optical counterpart candidate
  78. EP250711a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  79. Fermi GRB 250711A: Global MASTER-Net observations report
  80. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  81. GRB 250704A: GRANDMA observations
  82. GRB 250704A: SVOM/ECLAIRs refined analysis
  83. LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
  84. GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz
  85. GRB 250704B / EP250704a: 1.3 GHz MeerKAT Detection
  86. GRB 250702B,D,E / EP250702a: ALMA detection
  87. IceCube-250708A: No Candidates from WINTER
  88. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  89. GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA
  90. IceCube-250708A: Upper limits from a search for additional neutrino events in IceCube
  91. IPN triangulation of GRB 250704B (short/hard, consistent with EP 250704a)
  92. GRB 250706B/C: Insight-HXMT detection
  93. EP/WXT 01709181970: GOTO observations confirm stellar variability
  94. EP250704a/GRB 250704B: 10 GHz VLA detection
  95. GRB250702 B,D,E / EP250702a: MOSFIRE imaging of the afterglow
  96. IceCube-250706A: No Candidates from WINTER
  97. IPN triangulation of GRB 250706C (consistent with the GRB 250706B)
  98. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  99. GRB 250704B / EP250704a: VLA radio detection
  100. Fermi GRB 250708A: Global MASTER-Net observations report

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