Skip to main content
New! Browse Circulars by Event, Advanced Search, Sample Codes, Schema Release. 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. Fermi GRB 240715A: Global MASTER-Net observations report
  2. GRB 240713A: optical upper limits from the INAF Asiago Observatory
  3. GRB 240715A: Fermi GBM Observation
  4. GRB 240712A ATCA radio observations
  5. GRB240715A: GRANDMA Optical Upper Limits
  6. IPN triangulation of GRB 240715A (short)
  7. GW s240422ed: Swift UVOT follow-up
  8. GRB 240712A: Swift/UVOT Upper Limits
  9. EP-WXT flaring star and the optical flaring activity during its decay phase
  10. JinShan confirmation of the EP-WXT source triggered on July 14th due to a flaring star
  11. The EP-WXT source triggered on July 14th is likely a flaring star
  12. GRB 240715A: Fermi GBM Final Real-time Localization
  13. GRB 240713A: Tiled Swift observations
  14. GRB 240713A: J-band upper limit from WINTER
  15. GRB 240713A: NOT optical upper limits on three EP/FXT candidates
  16. GRB 240713A: JinShan optical upper limits
  17. GRB 240713A: OHP/T120 optical upper limit
  18. GRB240713A: X-ray follow-up observation with EP-FXT (duplicate submission of GCN 36859)
  19. GRB240713A: X-ray follow-up observation with EP-FXT
  20. GRB 240713B: AstroSat CZTI detection of a long burst
  21. GRB240713A: Optical upper limit with Kinder observations
  22. Fermi Sub-threshold Observation of GRB240713A
  23. GRB240713A: TAROT and GRANDMA Observations of SVOM/ECLAIRs GRB240713A
  24. GRB240713A : The first probable GRB Located on-Board SVOM by ECLAIRs
  25. Fermi Gamma-ray Burst Monitor trigger 742413075/240711744 is not a GRB
  26. EP240708a: GSP optical upper limit
  27. GRB 240712A: Swift detection of a burst
  28. LIGO/Virgo/KAGRA S240711cm: Coverage and upper limits from MAXI/GSC observations
  29. GRB 240711A: Fermi GBM Final Real-time Localization
  30. Fermi trigger No 742405878: Global MASTER-Net observations report
  31. LIGO/Virgo/KAGRA S240627by: Updated Sky localization and EM Bright Classification
  32. Fermi trigger No 742317942: Global MASTER-Net observations report
  33. EP240708a: KAIT optical upper limit
  34. Fermi GRB 240710A: Global MASTER-Net observations report
  35. GRB 240710A: Fermi GBM Final Real-time Localization
  36. EP240708a: NOT optical observations
  37. EP240708a: SVOM/C-GFT optical upper limit
  38. EP240708a: X-ray follow-up observations with EP/FXT and Swift/XRT
  39. EP240708a: Optical upper limits with Kinder observations
  40. EP240708a: EP-WXT detection of a fast X-ray transient
  41. LIGO/Virgo S240615dg: Swift XRT observations, 28 futher X-ray sources
  42. EP240703b: GSP optical upper limit
  43. Fermi Gamma-ray Burst Monitor trigger 741911057/240705933 is not a GRB
  44. GRB 240705A: Fermi GBM Final Real-time Localization
  45. EP240703b: TRT optical upper limits
  46. EP240703a: TRT further optical observation
  47. EP240702a: TRT optical upper limits
  48. Konus-Wind detection of GRB 240627A
  49. IPN triangulation of GRB 240628B (short)
  50. LIGO/Virgo/KAGRA S240705at: Updated Sky localization
  51. EP240703a and EP240703b: Swift/XRT upper limits
  52. LIGO/Virgo/KAGRA S240705at: Identification of a GW compact binary merger candidate
  53. EP240703a: KAIT optical upper limit
  54. EP240703a: BTA observations
  55. EP240703c: Kinder optical follow-up and Swift XRT observations
  56. EP240703a: BOOTES-3 optical upper limit
  57. EP240703a: Liverpool Telescope optical follow-up observations
  58. EP240703a/GRB 240703A: TRT optical candidate likely not real
  59. EP240703a: Kinder optical follow-up observations
  60. EP240703c: EP-WXT detection of an X-ray transient
  61. LIGO/Virgo/KAGRA S240703ad: Updated Sky localization
  62. LIGO/Virgo/KAGRA S240703ad: Identification of a GW compact binary merger candidate
  63. EP240703a/GRB 240703A: TRT and JinShan decaying optical afterglow candidate
  64. IPN triangulation of GRB 240627A
  65. GRB 240619A: Host galaxy redshift from VLT/X-shooter
  66. LIGO/Virgo/KAGRA S240422ed: Updated significance estimate
  67. The first three GRBs detected by SVOM: X-ray Upper Limits from EP-WXT
  68. EP240703b: EP-WXT detection of a fast X-ray transient
  69. Konus-Wind detection of GRB 240703A (a counterpart of EP240703a)
  70. EP240702a: Swift/XRT upper limit
  71. EP240703a: EP-WXT detection of a fast X-ray transient
  72. EP240702a: GSP optical upper limit
  73. The first three GRBs detected by SVOM: GRB 240627B, GRB 240629A and GRB 240702A
  74. GRB 240702A: BALROG localization (Fermi Trigger / GRB 240702885)
  75. Fermi GRB 240702A: Global MASTER-Net observations report
  76. GRB 240702A: Fermi GBM Final Real-time Localization
  77. EP240702a: EP-WXT detection of a fast X-ray transient
  78. LIGO/Virgo/KAGRA S240627by: Upper limits from Swift/BAT-GUANO
  79. Fermi Gamma-ray Burst Monitor trigger 741448122/240630575 is not a GRB
  80. GRB 240627A: CALET Gamma-Ray Burst Monitor detection
  81. Fermi trigger No 741448122: Global MASTER-Net observations report
  82. LIGO/Virgo/KAGRA S240630t: Updated Sky localization
  83. LIGO/Virgo/KAGRA S240629by: Updated Sky localization
  84. LIGO/Virgo/KAGRA S240630t: Identification of a GW compact binary merger candidate
  85. LIGO/Virgo/KAGRA S240629by: Upper limits from Fermi-GBM Observations
  86. LIGO/Virgo/KAGRA S240629by: Coverage and upper limits from MAXI/GSC observations
  87. Fermi trigger No 741356809: Global MASTER-Net observations report
  88. Fermi GRB 240629A: Global MASTER-Net observations report
  89. Fermi Gamma-ray Burst Monitor trigger 741362867/240629589 is not a GRB
  90. Fermi Gamma-ray Burst Monitor trigger 741288821/240628732 is not a GRB
  91. GRB 240629A: BALROG localization (Fermi Trigger 741372837 / GRB 240629704)
  92. GRB 240629A: Fermi GBM Final Real-time Localization
  93. Fermi Gamma-ray Burst Monitor trigger 741356809/240629519 is not a GRB
  94. LIGO/Virgo/KAGRA S240629by: Identification of a GW compact binary merger candidate
  95. Fermi trigger No 741296200: Global MASTER-Net observations report
  96. Fermi trigger No 741251380: Global MASTER-Net observations report
  97. IPN triangulation of GRB 240619C
  98. IceCube-Cascade 240626A: Upper limits from a search for additional neutrino events in IceCube
  99. GRB 240628A: BALROG localization (Fermi Trigger 741288821 / GRB 240628732)
  100. GRB 240627A: NuSTAR Detection of the long GRB

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