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"
  1. GRB 210202A: Fermi GBM detection
  2. GRB 210202A: Fermi-LAT detection
  3. Fermi GRB 210202A: Global MASTER-Net observations report
  4. Fermi trigger No 633963272: Global MASTER-Net observations report
  5. Recent activity of SGR 1935+2154 as observed by CGBM
  6. GRB 210202A: BALROG localization (Fermi Trigger / GRB 210202841)
  7. INTEGRAL detection of a short burst from SGR 1935+2154
  8. GRB 210202A: Fermi GBM Final Real-time Localization
  9. GRB 210131A: GECAM detection
  10. Fermi trigger No 633879387: Global MASTER-Net observations report
  11. GECAM observations of SGR 1935+2154
  12. GRB 210129A: Insight-HXMT/HE detection
  13. Continued Chandra observations of GW170817 at ~3.3 years since merger
  14. Fermi GBM Observations of SGR J1935+2154
  15. Konus-Wind detection of two bright bursts from SGR 1935+2154
  16. GRB 140330A: Swift-XRT refined Analysis
  17. GRB 140320B: Swift-XRT refined Analysis
  18. GRB 140402A: Swift-XRT refined Analysis
  19. GRB 140104B: Swift-XRT refined Analysis
  20. GRB 210126A: AstroSat CZTI detection
  21. GRB 210124B: AstroSat CZTI detection
  22. GRB 210123A: AstroSat CZTI detection
  23. IPN triangulation of a bright burst from SGR 1935+2154
  24. ZTF21aaeyldq: Observations with the 3.6m DOT
  25. GECAM detection of a short burst probably from SGR 1935+2154
  26. GRB 210127A: Fermi GBM Final Real-time Localization
  27. GRB 210120A: Fermi GBM detection
  28. Fermi trigger No 633348010: Global MASTER-Net observations report
  29. HAWC Transient event on 2021/01/25
  30. Konus-Wind detection of GRB 210121A
  31. Konus-Wind detection of GRB 210124B
  32. GRB 210126A: GECAM detection
  33. IPN triangulation of GRB 210124B (short)
  34. GRB 210126A: BALROG localization (Fermi Trigger / GRB 210126417)
  35. GRB 210124B: Insight-HXMT/HE detection
  36. Fermi trigger No 633257525: Global MASTER-Net observations report
  37. GRB 210123A: Fermi GBM Final Localization
  38. GECAM detection of a burst possibly from the X-ray burster 4U 0614+09 or GRB 210124A
  39. GRB 210123A: Insight-HXMT/HE detection
  40. IPN triangulation of GRB 210121A
  41. GRB 210121A: GECAM detection
  42. GRB 210121A: Insight-HXMT/HE detection
  43. GRB 210120A : 1.3m DFOT optical observations
  44. ZTF21aaeyldq: GROND and CAHA jet break confirmation
  45. ZTF20aaeyldq: VLA radio detection
  46. GRB 210116A: AstroSat CZTI detection
  47. GRB 210120A(MASTER OT J105242.66+152355.0 / AT2021axc): Mondy optical observations
  48. GRB 210116: AstroSat LAXPC detection
  49. GRB 210120A: MASTER OT (possibly) discovery
  50. GECAM In-Flight Trigger of GRB 210120A
  51. GRB 210104A: 3.6m DOT optical upper limit
  52. Fermi GRB 210120A: Global MASTER-Net observations report
  53. GRB 210120A: BALROG localization (Fermi Trigger 632819449 / GRB 210120299)
  54. GRB 210120A: Fermi GBM Final Real-time Localization
  55. GRB 210112A: 3.6m DOT optical detection
  56. GRB 210119A (Swift J1851.2-6148): Swift-BAT refined analysis
  57. GECAM detection of a short GRB 210119A or a new SGR candidate Swift J1851.2-6148
  58. ZTF21aaeyldq: GROND observations
  59. GRB 210119A: Insight-HXMT/HE detection
  60. GRB 210119A: Fermi GBM observation
  61. ZTF21aaeyldq: LBT near-infrared observations
  62. GRB 210112A: Insight-HXMT/HE detection
  63. Short Fermi GRB 210119A or new SGR Swift J1851.2-6148: Possible MASTER Short OT detection
  64. Fermi GRB 210119A: Global MASTER-Net observations report
  65. Swift detection of a new SGR Swift J1851.2-6148 or a short GRB 210119A
  66. GRB 210119A: Fermi GBM Final Real-time Localization
  67. ZTF21aaeyldq CAHA 2.2m detection and power-law decay
  68. GRB 200613A: Host galaxy redshift from OSIRIS/GTC
  69. GRB 210112A: Deep CAHA 2.2m detection
  70. GRB 210104A: Late-time CAHA 2.2m detection
  71. Fermi trigger No 632573937: Global MASTER-Net observations report
  72. ZTF21aaeyldq: KPED observations
  73. Konus-Wind detection of GRB 210112A
  74. Correction to GCN 29288: NuEm-210111A: No counterpart candidates in INTEGRAL SPI-ACS observation
  75. ZTF21aaeyldq (AT2021any): Detection of X-ray Emission with Swift/XRT
  76. ZTF21aaeyldq: 2.2m CAHA BVRI optical observations
  77. GRB 201221D: near-infrared observation with LBT
  78. ZTF21aaeyldq: NOT optical observations
  79. ZTF21aaeyldq: Lowell Discovery Telescope observations
  80. ZTF21aaeyldq: observations with the 3.6m Devasthal Optical Telescope
  81. ZTF21aaeyldq: GTC Redshift and GRB afterglow nature confirmation
  82. GRB 201015A: evidence of supernova in LBT spectra
  83. ZTF Discovery of ZTF21aaeyldq (AT2021any): a Hostless, Young, and Rapidly Fading Transient
  84. GRB 210104A: JCMT SCUBA-2 sub-mm observations
  85. GRB 210112A: Swift/UVOT Detection
  86. GRB 210112A: Mondy optical observations
  87. GRB 210112A: 1.3m DFOT Optical upper limit
  88. GRB 210112A: OSN second epoch, decay
  89. GRB 210104A: AstroSat CZTI detection
  90. NuEm-210111A: MAXI/GSC upper limit
  91. GRB 210112A: Swift-BAT refined analysis
  92. GRB 210112A: OSN Reddened Afterglow Detection
  93. GRB 210112A: Swift-XRT refined Analysis
  94. NuEm-210111A : No neutrino counterpart in ANTARES
  95. GRB 210112A: AGILE detection
  96. GRB 210112A: Kitab a optical upper limit
  97. GRB 210104A: AROMA-N Optical Afterglow Detection
  98. GRB 210112A: Enhanced Swift-XRT position
  99. GRB 210112A: Swift detection of a burst with an optical counterpart
  100. NuEm-210111A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt 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