Skip to main content
New! Browse Circulars by Event, Advanced Search, Sample Codes, Schema Release. 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"

18647 results found.

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

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