Skip to main content
JSON Notices via Email, Kafka Cron Jobs, Submitter Profile, GCN is Hiring. 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"

45687 results found.

  1. GRB 250221A: VLT/X-shooter redshift z = 0.768
  2. GRB 250221A: GRANDMA/TAROT Detection
  3. Fermi trigger No 761805304: Global MASTER-Net observations report
  4. Fermi Gamma-ray Burst Monitor trigger 761867337/250221909 is not a GRB
  5. GRB 250221A: Swift-XRT refined Analysis
  6. GRB 250221A: NOT optical observations
  7. GRB 250221A: 1.6m Mephisto optical detection
  8. LIGO/Virgo/KAGRA S250221gb: Retraction of GW compact binary merger candidate
  9. GRB 250221A: AKO Optical Upper Limit
  10. GRB 250221A: Swift/UVOT Detection
  11. EP250220a: Liverpool Telescope upper limits
  12. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  13. GRB 250221A: REM optical/NIR afterglow detection
  14. IceCube-250207A: MASTER flaring blazar QSOJ0854+2006 with Zhirkov effect
  15. GRB 250221A: Enhanced Swift-XRT position
  16. LIGO/Virgo/KAGRA S250221eb: Retraction of GW compact binary merger candidate
  17. EP250220a: 1.6m Mephisto observations
  18. EP250220a: Liverpool Telescope optical upper limits
  19. EP250220a: Optical upper limit with Kinder observations
  20. SVOM trigger sb25022102 is not an astrophysical event
  21. SVOM/sb25022102: SVOM detection of an X-ray transient
  22. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  23. GRB 250221A: Swift detection of a burst with an optical counterpart
  24. Swift GRB250221.15: Global MASTER-Net OT detection
  25. Swift GRB250221.15: Global MASTER-Net observations report
  26. EP250220a: Xinglong optical upper limit
  27. Fermi Gamma-ray Burst Monitor trigger 761788229/250220993 is not a GRB
  28. GRB 250220B: Fermi GBM Final Real-time Localization
  29. Fermi Gamma-ray Burst Monitor trigger 761782146/250220923 is not a GRB
  30. GRB 250220A: Fermi GBM Final Real-time Localization
  31. EP250220a: Global MASTER-Net observations report
  32. EP250220a: EP-WXT detection of a fast X-ray transient
  33. Konus-Wind detection of GRB 250217C (short)
  34. GRB 250219A: Swift/UVOT Upper Limits
  35. GRB 250219A: OHP/T193 optical upper limit
  36. GRB 250219A: NOT optical observations
  37. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  38. GRB 250219A: 1.6m Mephisto optical upper limits
  39. GRB 250219A: SVOM/VT optical counterpart
  40. GRB 250219A: Swift-XRT observations
  41. LIGO/Virgo/KAGRA S250206dm: Upper limits from MSU cubesats observations
  42. GRB 250219A: Swift ToO observations
  43. GRB 250219A: SVOM detection of a burst
  44. Konus-Wind detection of GRB 250215A / EP250215a
  45. SVOM/sb25021804: COLIBRÍ/DDRAGO Confirmation of Variability
  46. GRB 250217C: Swift-XRT observations
  47. SVOM/sb25021804: QSO variability in Liverpool Telescope observations
  48. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  49. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  50. GRB 250217C: SVOM/GRM observation
  51. GRB 250217C: Tiled Swift observations
  52. GRB 250217C: Fermi GBM Observation
  53. GRB 250215A / EP250215A: Encouraging Follow-up Observations of a BdHN I with a Rest-Frame Duration 2.3 s at z=4.61
  54. IPN triangulation of GRB 250217C (short)
  55. Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
  56. SVOM/sb25021804: SVOM detection of a long X-ray transient
  57. GRB 250213A: Swift-XRT observations
  58. LIGO/Virgo/KAGRA S250206dm: AZT-33IK Target Optical Observations
  59. GRB 250216A: AstroSat CZTI detection
  60. GRB 250217C: AstroSat CZTI detection of a short burst
  61. Fermi GRB 250217C: Global MASTER-Net observations report
  62. GRB 250217C: Fermi GBM Final Real-time Localization
  63. IceCube-Cascade 250215A: Upper limits from a search for additional neutrino events in IceCube
  64. LIGO/Virgo/KAGRA S250206dm: observation in AbAO, optical transient near NED/GLADE+ galaxy WISEA J021210.14+514821.7
  65. Fermi GRB 250217A: Global MASTER-Net observations report
  66. GRANDMA/OPD observations of GRB250215A
  67. GRB 250217B: Fermi GBM Final Real-time Localization
  68. The EP-WXT trigger 01709131775 is likely a flaring star
  69. GRB 250217A: Fermi GBM Final Real-time Localization
  70. Fermi GRB 250216A: Global MASTER-Net observations report
  71. GRB 250215A / EP250215a: LCO detection of the afterglow
  72. GRB 250216A: Fermi GBM Final Real-time Localization
  73. EP250212a: FTW optical and NIR upper limits
  74. GRB 250215A: Swift/UVOT Upper Limits
  75. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  76. EP250215a / GRB 250215A : GTC redshift z = 4.61
  77. GRB 250215A: Fermi GBM Observation
  78. EP250215a / GRB 250215A : NOT optical observations
  79. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  80. GRB 250215A / EP250215a: Gemini-South optical observation of a likely rebrightening
  81. LIGO/Virgo/KAGRA S250206dm: MASTER LC AT2025bbo
  82. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  83. GRB 250215A: Swift-XRT refined Analysis
  84. GRB 250215A: SVOM/GRM observation
  85. EP250215a / GRB 250215A: AstroSat CZTI detection
  86. GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation
  87. EP250215a: Global MASTER-Net observations report
  88. EP250215A/GRB 250215A: INTEGRAL SPI-ACS detection
  89. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  90. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  91. Fermi GRB 250215A: Global MASTER-Net observations report
  92. GRB 250215A: Fermi GBM Final Real-time Localization
  93. Fermi trigger No 761206993: Global MASTER-Net observations report
  94. GRB 250213A：SVOM/VT optical candidate
  95. Fermi Gamma-ray Burst Monitor trigger 761206993/250214266 is not a GRB
  96. EP250207b: Xinglong optical upper limit
  97. Fermi GRB 250214A: Global MASTER-Net observations report
  98. GRB 250213A: Swift ToO observations
  99. GRB 250214A: Fermi GBM Final Real-time Localization
  100. EP250212a: Xinglong optical upper limit

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