Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! 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"
  1. IceCube-230707A: No candidates detected by Swift-XRT
  2. Swift Trigger 1178410 is not an astrophysical event
  3. GRB 230709C: AstroSat CZTI detection
  4. LIGO/Virgo/KAGRA S230708cf: Updated Sky localization
  5. GRB 230707B: CALET Gamma-Ray Burst Monitor detection
  6. GRB 230703A detected with multiple GRID detectors
  7. GRB 230709C: BALROG localization (Fermi Trigger 710617111 / GRB 230709735)
  8. LIGO/Virgo/KAGRA S230707ai: Updated Sky localization
  9. IceCube-230707A: No candidates from the Zwicky Transient Facility
  10. Fermi-LAT gamma-ray observations of IceCube-230708A
  11. Fermi-LAT gamma-ray observations of IceCube-230707B
  12. Fermi-LAT gamma-ray observations of IceCube-230707A
  13. LIGO/Virgo/KAGRA S230630am: Updated Sky localization
  14. LIGO/Virgo/KAGRA S230630am: Updated Sky localization
  15. GRB 230709B: BALROG localization (Fermi Trigger 710614579 / GRB 230709706)
  16. IceCube-230708A: Upper limits from a search for additional neutrino events in IceCube
  17. IceCube-230707B: Upper limits from a search for additional neutrino events in IceCube
  18. IceCube-230707A: Upper limits from a search for additional neutrino events in IceCube
  19. LIGO/Virgo/KAGRA S230709bi: Identification of a GW compact binary merger candidate
  20. Swift Trigger 1178410: possible GRB 230709A
  21. LIGO/Virgo/KAGRA S230708cf: Identification of a GW compact binary merger candidate
  22. LIGO/Virgo/KAGRA S230708bi: Retraction of GW compact binary merger candidate
  23. GRB 230628C: GRID Detection
  24. IceCube-230708A - IceCube observation of a high-energy neutrino candidate track-like event
  25. GRB 230707B: Swift/BAT-GUANO detection of a burst outside the coded FOV
  26. GRB 230707A: Swift-XRT observations
  27. IceCube Alert 230708.35: Global MASTER-Net observations report
  28. IceCube-230707B - IceCube observation of a high-energy neutrino candidate track-like event
  29. GRB 230707B: Fermi GBM Final Real-time Localization
  30. IceCube Alert 230707.71: Global MASTER-Net observations report
  31. IceCube-230707A - IceCube observation of a high-energy neutrino candidate track-like event
  32. GRB 230707A: Fermi GBM Detection
  33. LIGO/Virgo/KAGRA S230707ai: Identification of a GW compact binary merger candidate
  34. GRB 230707A: Swift ToO observations
  35. GRB 230707A: Swift/BAT-GUANO arcminute localization of a burst
  36. ZTF23aaoohpy/AT2023lcr : HCT follow-up observations
  37. Fermi GRB 230707A: Global MASTER-Net observations report
  38. GRB 230707A: Fermi GBM Final Real-time Localization
  39. LIGO/Virgo/KAGRA S230706ah: Updated Sky localization
  40. Integral GRB230706.70: Global MASTER-Net observations report
  41. LIGO/Virgo/KAGRA S230704f: Updated Sky localization
  42. LIGO/Virgo/KAGRA S230630bq: Updated Sky localization
  43. IBAS trigger number 10311: not a real GRB
  44. LIGO/Virgo/KAGRA S230702an: Updated Sky localization
  45. GRB 230625A: Detection by GRID
  46. LIGO/Virgo/KAGRA S230529ay: Updated Sky localization and EM Bright Classification
  47. LIGO/Virgo/KAGRA S230706ah: Identification of a GW compact binary merger candidate
  48. LIGO/Virgo/KAGRA S230627c: GECKO optical follow-up observations of host galaxy candidates and ZTF23aaptsuy/AT2023lxu
  49. ZTF23aaoohpy/AT2023lcr: AMI-LA radio detection
  50. Fermi trigger No 710117592: Global MASTER-Net observations report
  51. GRB 230626A: VZLUSAT-2 detection
  52. LVK S230619bd/GBM-230619: Upper limits from a two-week IceCube neutrino search
  53. GRB 230328B: LBT detection of the likely host galaxy
  54. LIGO/Virgo/KAGRA S230704f: Identification of a GW compact binary merger candidate
  55. Konus-Wind detection of GRB 220623A
  56. GRB 230701B: AstroSat CZTI detection
  57. LIGO/Virgo/KAGRA S230627c: observations of ZTF23aaptsuy/AT2023lx in AbAO observatory
  58. LIGO/Virgo/KAGRA S230702an: Identification of a GW compact binary merger candidate
  59. GRB 230628E: Swift/UVOT Detection
  60. GRB 230628E: Swift-BAT refined analysis
  61. GRB 230702A: Fermi GBM Final Real-time Localization
  62. GRB 230628E: ATCA rapid radio follow-up
  63. GRB 230701A: Fermi GBM Final Real-time Localization
  64. LIGO/Virgo/KAGRA S230627c: GRANDMA observations of galaxies and ZTF counterpart candidates
  65. LIGO/Virgo/KAGRA low-significance gravitational wave candidate S230701z: one counterpart neutrino candidate from IceCube neutrino searches
  66. LIGO/Virgo/KAGRA S230627c: Upper limits from Swift/BAT-GUANO
  67. LIGO/Virgo/KAGRA S230630bq: Identification of a GW compact binary merger candidate
  68. IPN triangulation of GRB 230625B (ultra-long)
  69. AT2023lcr (ATLAS23msn/ZTF23aaoohpy): ALMA 100 GHz Detection
  70. LIGO/Virgo/KAGRA S230630am: Identification of a GW compact binary merger candidate
  71. GRB 230625B: CALET Gamma-Ray Burst Monitor detection
  72. GRB 230628E - VLT spectroscopic observations
  73. ZTF23aaoohpy/AT2023lcr: LBT observations
  74. Fermi GRB 230628C: Global MASTER-Net observations report
  75. GRB 230625B: AstroSat CZTI detection
  76. GRB230628E: VLT optical identification of afterglow candidate
  77. GRB 230628E: Swift-XRT refined Analysis
  78. GRB 230628E: Enhanced Swift-XRT position (Correction to name in GCN 34115)
  79. GRB 230628A: Enhanced Swift-XRT position
  80. Fermi GRB 230628D: Global MASTER-Net observations report
  81. LIGO/Virgo/KAGRA S230628ax: Identification of a GW compact binary merger candidate
  82. GRB 230628E: LCOGT Optical Upper Limit
  83. Swift GRB230628.93: Global MASTER-Net observations report
  84. GRB 230628E: Swift detection of a burst
  85. GRB 230628D: BALROG localization (Fermi Trigger 709676556 / GRB 230628849)
  86. GRB 230628D: Fermi GBM Final Real-time Localization
  87. LIGO/Virgo/KAGRA low-significance gravitational wave candidate S230628aj: one counterpart neutrino candidate from IceCube neutrino searches
  88. GRB 230628C: Fermi GBM Final Real-time Localization
  89. GRB 230628B: Swift/BAT-GUANO detection of a burst outside the coded FOV
  90. GRB 230623B: CALET Gamma-Ray Burst Monitor detection
  91. LIGO/Virgo/KAGRA S230516az: GOTO candidate counterpart GOTO23hu ruled out by Zwicky Transient Facility observations
  92. ZTF23aaoohpy /AT2023lcr: TNG NIR detection
  93. GRB 230628A: Fermi GBM Final Localization
  94. LIGO/Virgo/KAGRA S230627c: Additional observations from the Zwicky Transient Facility
  95. GRB 230626A: GRBAlpha detection
  96. AT2023lcr: JCMT SCUBA-2 sub-mm observations
  97. LIGO/Virgo/KAGRA S230527c: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  98. LIGO/Virgo/KAGRA S230627c: ATLAS information on the ZTF candidates
  99. LIGO/Virgo/KAGRA S230627c: Upper limits from Fermi-GBM Observations
  100. GRB230626A: Fermi GBM Detection

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