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"

43117 results found.

  1. GRB 250215A: Fermi GBM Observation
  2. EP250215a / GRB 250215A : NOT optical observations
  3. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  4. GRB 250215A / EP250215a: Gemini-South optical observation of a likely rebrightening
  5. LIGO/Virgo/KAGRA S250206dm: MASTER LC AT2025bbo
  6. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  7. GRB 250215A: Swift-XRT refined Analysis
  8. GRB 250215A: SVOM/GRM observation
  9. EP250215a / GRB 250215A: AstroSat CZTI detection
  10. GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation
  11. EP250215a: Global MASTER-Net observations report
  12. EP250215A/GRB 250215A: INTEGRAL SPI-ACS detection
  13. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  14. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  15. Fermi GRB 250215A: Global MASTER-Net observations report
  16. GRB 250215A: Fermi GBM Final Real-time Localization
  17. Fermi trigger No 761206993: Global MASTER-Net observations report
  18. GRB 250213A：SVOM/VT optical candidate
  19. Fermi Gamma-ray Burst Monitor trigger 761206993/250214266 is not a GRB
  20. Fermi GRB 250214A: Global MASTER-Net observations report
  21. GRB 250213A: Swift ToO observations
  22. GRB 250214A: Fermi GBM Final Real-time Localization
  23. LIGO/Virgo/KAGRA S250206dm: DECam GW-MMADS candidates
  24. GRB 250213A: SVOM detection of a burst
  25. EP250212a: Global MASTER-Net observations report
  26. GRB 250205A: VIRT Optical Upper Limit
  27. GRB 250205A: Leavitt Observatory optical upper limit
  28. GRB 250210A: GRBAlpha detection
  29. EP250207B: Chandra localization of the X-ray counterpart
  30. LIGO/Virgo/KAGRA S250206dm: FTW observations of counterpart candidates AT2025bbo and AT2025bcx, and of NED galaxies
  31. EP250207b: VLA radio upper limits
  32. EP250212a: Liverpool Telescope optical upper limits
  33. EP250212a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  34. GRB250101A: Radio upper limits from GMRT observations
  35. EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
  36. EP250207B: GTC z-band Observations
  37. Fermi GRB 250212A: Global MASTER-Net observations report
  38. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
  39. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  40. Fermi trigger No 760945500: Global MASTER-Net observations report
  41. EP250207b: NOT optical counterpart candidate
  42. GRB 250211A: SVOM trigger sb25021103 is not a GRB
  43. GRB 250211B: A long GRB detected by INTEGRAL
  44. LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
  45. GRB 250211A: Swift ToO observations
  46. Integral GRB250211.89: Global MASTER-Net observations report
  47. GRB 250212A: Fermi GBM Final Real-time Localization
  48. LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
  49. LIGO/Virgo/KAGRA S250211be: Updated Sky localization
  50. GRB 250207A: Fermi GBM Observation
  51. GRB 250206A: Fermi GBM Observation
  52. GRB 250205A / EP250205A: radio detection with the VLA
  53. IceCube-250207A: One candidate from the Zwicky Transient Facility
  54. EP250207b: Tentative z-band brightening source
  55. LIGO/Virgo/KAGRA S250206dm: continued in SOAR galaxy targeted observations and identification of one possible transient
  56. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo
  57. Konus-Wind detection of GRB 250207A
  58. Konus-Wind detection of GRB 250206A
  59. GRB 250210A: SVOM/GRM observation of a long burst
  60. EP250207b: Liverpool Telescope possible optical counterpart
  61. EP250207b: Global MASTER-Net observations report
  62. Gemini-South spectroscopic redshift of EP250207b host galaxy candidate (z=0.082)
  63. LIGO/Virgo/KAGRA S250211be: Identification of a GW compact binary merger candidate
  64. LIGO/Virgo/KAGRA S250211aa: Updated Sky localization and EM Bright Classification
  65. LIGO/Virgo/KAGRA S250211aa: Identification of a GW compact binary merger candidate
  66. GRB 250207A: Skynet optical afterglow observations
  67. LIGO/VIRGO/KAGRA S250206dm: AT 2025bbo spectroscopic observations with NIRES on Keck II
  68. LIGO/Virgo/KAGRA S250206dm: Gemini-North spectroscopic observation of AT2025bbo and its host galaxy
  69. GRB 241128A: VIRT Optical Upper Limit
  70. EP250207b: Gemini GMOS-N z-band observations
  71. EP250207A: Upper limits from Fermi-GBM Observations
  72. GRB 250210A: INTEGRAL SPI-ACS detection
  73. GRB 250210A: AstroSat CZTI detection
  74. EP250207b: a new X-ray transient detected by Einstein Probe
  75. LIGO/Virgo/KAGRA S250206dm: MASTER detection AT2025bbo
  76. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  77. Fermi GRB 250210A: Global MASTER-Net observations report
  78. GRB 250210A: Fermi GBM Final Real-time Localization
  79. LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
  80. IceCube-250207A: Upper limits from a search for additional neutrino events in IceCube
  81. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  82. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of AT2025bbo and Galaxies in the Localization Volume
  83. IceCube Alert 250207.09: Global MASTER-Net observations report
  84. LIGO/Virgo/KAGRA S250206dm: Observations from WINTER
  85. GRB 250204B: GRBAlpha detection
  86. GRB 250204A: GRBAlpha detection
  87. LIGO/Virgo/KAGRA S250206dm & FRB 20250206A: MASTER observations and possible mother galaxy
  88. LIGO/Virgo/KAGRA S250206dm: Optical observations of candidate AT 2025bbo with Kinder
  89. Fermi-LAT Gamma-ray Observations of IceCube-250207A
  90. GRB 250207A: 1.3m DFOT Optical observations
  91. LIGO/Virgo/KAGRA S250206dm: WFST follow-up observations
  92. GRB 250206A: Swift-XRT observations
  93. LIGO/Virgo/KAGRA S250206dm: FRB 20250206A BOOTES-5 and 2.2m CAHA optical upper limits
  94. GRB 250129A: GRANDMA Continued Afterglow Detection
  95. LIGO/Virgo/KAGRA S250206dm: further Pan-STARRS observations and one candidate AT2025bbo
  96. LIGO/Virgo/KAGRA S250207bg: Updated NED Galaxies in the Localization Volume
  97. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  98. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  99. GRB 250205A: 1.3m DFOT optical upper limit
  100. GRB 250206A: Tiled Swift observations

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