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"

19359 results found.

  1. GRB 250717B: SVOM/GRM observation
  2. GRB 250721A: Tiled Swift observations
  3. GRB 250717B: COLIBRÍ optical upper limit
  4. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  5. GRB 250717B: Swift-XRT observations
  6. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  7. Swift Trigger 1334535: a possible GRB 250718A
  8. Swift GRB250718.01: Global MASTER-Net observations report
  9. GRB 250717B: Swift ToO observations
  10. GRB 270713A: Kitab and AbAO Optical Observations
  11. GRB 250717B: Fermi GBM Observation
  12. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  13. GRB 250716A: Swift-XRT afterglow detection
  14. GRB 250716A: Swift ToO observations
  15. GRB 250713A: SVOM/C-GFT upper limit
  16. GRB 250713A: Swift-XRT observations
  17. GRB 250706A: Swift-BAT refined analysis
  18. GRB 250702F: Swift-BAT refined analysis
  19. GRB 250628A: Swift-BAT refined analysis
  20. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  21. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  22. GRB 250702B,D,E/EP250702A: MeerKAT radio observations at 1.28GHz
  23. GRB250702 B,D,E / EP250702a: MOSFIRE imaging of the afterglow
  24. GRB 250706B/C: Fermi-LAT detection
  25. GRB 250706B: Swift/UVOT Detection
  26. EP250702a/ GRB 250702B: NuSTAR X-ray Observations
  27. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  28. GRB 250702F: GRANDMA observations
  29. GRB 250706A: Swift-XRT refined Analysis
  30. GRB 250706A: Swift/UVOT Upper Limits
  31. GRB 250706A: REM optical/NIR observations
  32. Swift GRB 250706A: Global MASTER-Net observations report
  33. GRB 250706A: JinShan optical upper limits
  34. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  35. GRB250706B: Swift-XRT counterpart detection
  36. GRB 250706A: GROWTH-India Telescope optical upper limit
  37. GRB 250706A: Swift detection of a burst
  38. GRB 250704B: Swift-XRT refined Analysis
  39. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  40. GRB 250704B: Swift/UVOT Upper Limits
  41. GRB 250704A: Swift/UVOT Detection
  42. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  43. GRB 250702F: Kilonova-Catcher optical afterglow detection
  44. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  45. GRB 250704A: SVOM/VT optical observation
  46. GRBs 250702B,D,E / EP250702a: fast fading, extremely red counterpart
  47. EP250704a / GRB 250704B: SVOM/VT optical blue counterpart
  48. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  49. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  50. GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
  51. EP250704a / GRB250704B: Swift-XRT counterpart detection
  52. GRB 250704A: Swift-XRT afterglow detection
  53. GRB 250702B / EP2050702a: FTW optical and NIR observations
  54. Konus-Wind detection of GRB 250702F
  55. GRB 250702F: GROWTH-India Telescope optical observations
  56. EP250702a: WFST optical observations
  57. GRB 250702F: SVOM/VT optical observation
  58. GRB 250702F: Swift/UVOT Detection
  59. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  60. GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit
  61. GRB 250702F: Swift-XRT refined Analysis
  62. GRB 250702F: Fermi GBM Observation
  63. GRB 250702F: Leavitt Observatory optical observations
  64. GRB 250702F: AKO Optical Afterglow Detection
  65. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  66. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  67. GRB 250702F: Skynet Optical Observations
  68. GRB 250424A: VIRT Optical Upper Limit
  69. GRBs 250702B/C/D/E / EP250702a: Swift XRT localization
  70. GRB 250702F: TRT Optical Observation
  71. GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
  72. GRB 250702F: REM optical afterglow detection
  73. GRB 250702F: DDOTI Optical Observation
  74. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  75. GRB 250702F: COLIBRÍ Observations of the Afterglow
  76. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  77. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  78. GRB 250702F: Enhanced Swift-XRT position
  79. GRB 250702F: GTC/OSIRIS+ spectroscopic redshift z = 1.520
  80. GRB 250702F: NOT observations of the optical afterglow
  81. GRB 250702F: MASTER optical afterglow observation
  82. GRB 250702F: GOTO optical counterpart detection
  83. GRB 250702F: Ondrejov D50 optical afterglow detection
  84. GRB 250702F: Swift detection of a burst with an optical counterpart
  85. Swift GRB 250702F: Global MASTER-Net observations report
  86. GRB 250628B: Swift-XRT observations
  87. GRB 250628B: SVOM/VT optical upper limit
  88. GRB 250628A: REM optical/NIR upper limits
  89. GRB 250625A: VLT/X-shooter spectroscopic observations at the afterglow position
  90. GRB 250628A: VLT/X-shooter upper limits
  91. GRB 250628A: Swift/UVOT Upper Limits
  92. GRB 250628A: Swift-XRT refined Analysis
  93. Swift GRB 250628A: Global MASTER-Net observations report
  94. GRB 250628A: Enhanced Swift-XRT position
  95. GRB 250628A: Swift detection of a burst
  96. GRB 250625A: Swift-BAT refined analysis
  97. GRB 250625A: Leavitt Observatory afterglow detection
  98. GRB 250625A: GTC/OSIRIS+ spectroscopic observations of the potential host galaxy
  99. GRB 250625A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  100. GRB 250625A: SVOM/C-GFT upper limit in early phase

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