Skip to main content
New! BOOM Notices and Schema v7.0.0. 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"

27320 results found.

  1. EP250108a: MeerKAT radio upper limit
  2. LIGO/Virgo/KAGRA S250114ax: Updated NED Galaxies in the Localization Volume
  3. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  4. LIGO/Virgo/KAGRA S250114ax: Updated Sky localization
  5. IPN triangulation of GRB 250113A
  6. GRB 250114B: Liverpool Telescope optical upper limit
  7. LIGO/Virgo/KAGRA S250114ax: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  8. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  9. GRB 250114B: Swift-XRT observations
  10. GRB 250114A: LCO optical counterpart detection.
  11. GRB 250114B: OHP/T193 optical upper limit
  12. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  13. GRB 250114A: Swift-XRT refined Analysis
  14. GRB 250114A: LCOGT optical afterglow i-band detection
  15. GRB 250114B : GIT optical upper limit
  16. EP250111a: SAO RAS optical upper limit
  17. LIGO/Virgo/KAGRA S250114ax: NED Galaxies in the Localization Volume
  18. GRB 250114B: a short GRB detected with INTEGRAL
  19. GRB 250114A: Enhanced Swift-XRT position
  20. GRB 250114A: REM detection of the optical and NIR counterpart
  21. LIGO/Virgo/KAGRA S250114ax: Identification of a GW compact binary merger candidate
  22. Swift GRB250114A: Global MASTER-Net OT detection
  23. GRB 250114A: LCO optical observations
  24. GRB 250114A: TRT optical observations
  25. GRB 250114A: Swift detection of a burst with an optical counterpart
  26. GRB 250101A: Terskol Zeiss-2000 optical observations
  27. EP250108a / AT 2025kg: SAO RAS optical observations
  28. EP241021a: SMA radio observation
  29. GRB 250113A: SVOM/GRM observation of a long burst
  30. GRB 250107A: VZLUSAT-2 detection
  31. EP250109b: optical upper limits with the Liverpool Telescope
  32. GRB 250106A: Swift-XRT afterglow detection
  33. EP250111a: KAIT optical observations
  34. GRB 250109A / EP250109a: Mephisto optical upper limits
  35. EP250108a: Mephisto detection
  36. EP250111a: Mondy optical observation
  37. EP250108a / AT 2025kg: LCO optical observations
  38. EP250108a / AT 2025kg: Swift UVOT detections
  39. EP250108a / AT 2025kg (the "kangaroo”): VLT/X-shooter spectroscopic redshift z = 0.176 and LFBOT classification
  40. EP250111a: NOT likely optical counterpart
  41. GRB 250101B: Fermi GBM Observation
  42. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  43. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  44. GRB 250108A: Swift/XRT afterglow fading
  45. LIGO/Virgo/KAGRA S250109bi: Updated Sky localization
  46. LIGO/Virgo/KAGRA S250109f: Updated Sky localization
  47. LIGO/Virgo/KAGRA S250108eo: Updated Sky localization
  48. EP-WXT trigger EP250108a：Xinglong optical follow-up observations
  49. GRB 250101A: CMO RC-500 optical observations
  50. GRB 250109A: Fermi GBM Observation
  51. EP250108a: NOT optical observations
  52. EP-WXT trigger EP250109a：Xinglong optical follow-up observations
  53. GRB 250109a: GMG Optical Upper Limit
  54. EP250109a: Swift/UVOT non-detection
  55. IPN triangulation of GRB 250107D (short/hard)
  56. EP250108a: Liverpool Telescope likely optical counterpart
  57. GRB 250108B: Swift-BAT refined analysis
  58. GRB 250108B: 1.3m DFOT upper limit
  59. GRB 250108B: REM optical/NIR upper limits
  60. GRB 250101A: Terskol K-800 optical observations
  61. EP250109a: Swift/XRT non-detection
  62. GRB 250108A: Swift/UVOT Upper Limits
  63. LIGO/Virgo/KAGRA S250109bi: Identification of a GW compact binary merger candidate
  64. GRB 250108A: NOT optical upper limit
  65. EP250108a: EP-WXT detection of an X-ray transient
  66. LIGO/Virgo/KAGRA S250109f: Identification of a GW compact binary merger candidate
  67. GRB 250108B: Swift-XRT refined Analysis
  68. GRB 250103A: 1.6m Mephisto optical observations
  69. GRB 250108A: Swift-XRT afterglow detection
  70. GRB 250108A:SVOM/VT optical candidate
  71. LIGO/Virgo/KAGRA S250108eo: Identification of a GW compact binary merger candidate
  72. GRB 250108B: Swift/UVOT Upper Limits
  73. GRB 250103A: Swift-XRT afterglow detection
  74. GRB 250108B: Enhanced Swift-XRT position
  75. GRB 250108B: Swift detection of a burst
  76. GRB 250107A: Fermi GBM Observation
  77. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  78. GRB 250106A: SVOM/VT 2nd optical deep observation
  79. GRB 250101A: J band upper limit by SYSU 80cm telescope
  80. EPWXT01709129925: Xinglong optical observations
  81. GRB 250106A: NOT optical observations
  82. LIGO/Virgo/KAGRA S250104v: Updated Sky localization
  83. GRB 250103B: REM optical/NIR upper limits
  84. GRB 250101A: REM optical/NIR counterpart detection
  85. GRB 250106A: Swift-XRT observations
  86. GRB 250106A: SVOM/VT optical candidate
  87. The EP-WXT trigger 01709129925 is likely a flaring star
  88. GRB 250103B: Swift-XRT refined Analysis
  89. GRB 250103B: LCO/1m optical afterglow candidate detection
  90. GRB 250103A: Bassano Bresciano Observatory upper limit
  91. GRB 250103A: Swift-XRT observations
  92. GRB 250101A: 1.3m DFOT optical afterglow detection
  93. GRB 241229A: 1.3m DFOT upper limit
  94. GRB 241228B: 1.3m DFOT Optical observations
  95. GRB 241228A: 1.3m DFOT upper limit
  96. LIGO/Virgo/KAGRA S250104v: Identification of a GW compact binary merger candidate
  97. GRB 250103A: Montarrenti Observatory optical detection
  98. GRB 250101A: further LCOGT optical afterglow observations
  99. GRB 250103A: TSHAO optical upper limit
  100. GRB 250103A: Fermi GBM Observation

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