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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. EP240802a/GRB240802A: KAIT optical upper limit
  2. GRB 240720B: VZLUSAT-2 detection
  3. GRB 240710A: VZLUSAT-2 detection
  4. EP240806A: Liverpool Telescope optical follow-up observations
  5. The EP-WXT trigger 01709018832 on August 7th is likely a flaring star
  6. GRB 240807A: Fermi GBM Final Localization
  7. EP240807a: EP-WXT detection of a fast X-ray transient
  8. EP240806a: Gemini North-GMOS spectroscopic redshift of z = 2.818
  9. GRB 240805B: GIT optical upper limit
  10. EP240806a: KAIT optical observations
  11. GRB 240805B: Swift-BAT refined analysis
  12. GRB 240805A: Swift-BAT refined analysis
  13. Fermi trigger No 744629911: Global MASTER-Net observations report
  14. EP240804a (GRB 240804B): NOT optical observations
  15. EP240806a: LCOGT optical counterpart detection
  16. Konus-Wind detection of GRB 240802A (EP240802a)
  17. Improved IPN triangulation of GRB 240802A / EP 240802a
  18. Konus-Wind detection of GRB 240805A
  19. GRB 240805B Bassano Bresciano Observatory upper limit
  20. GRB240805A: Fermi GBM Observation
  21. GRB 240805B: JinShan optical afterglow detection
  22. GRB 240804B/EP240804a: Correction to the GRB name in GCN 37071
  23. GRB 240805B: AbAO, CrAO, and Terskol optical upper limits
  24. Konus-Wind detection of GRB 240804B (a counterpart of EP240804a)
  25. Fermi Gamma-ray Burst Monitor trigger 240806402/744629911 is not a GRB
  26. EP240806a: EP-FXT detection of the X-ray emission
  27. GRB 240626B: VZLUSAT-2 detection
  28. GRB 240624B: VZLUSAT-2 detection
  29. GRB 240619C: VZLUSAT-2 detection
  30. EP 240806A: LCO optical observations
  31. EP240806a: GSP optical counterpart detection
  32. EP240806a: EP-WXT detection of a fast X-ray transient
  33. GRB 240805B: Optical detection with 1.6m Mephisto
  34. EP240804a: BOOTES-6/DPRT optical detection
  35. GRB 240805B: NUTTelA-TAO / BSTI Optical Limits
  36. GRB 240805B: Swift-XRT refined Analysis
  37. Fermi trigger No 744544656: Global MASTER-Net observations report
  38. GRB 240805B: Swift/UVOT Upper Limits
  39. GRB 240805A: Swift/UVOT Upper Limits
  40. GRB 240805B: BTA optical afterglow candidate
  41. GRB 240805A: SVOM/GRM observation
  42. GRB 240805B: Enhanced Swift-XRT position
  43. GRB 240805B: LCOGT Optical Upper Limits
  44. Swift GRB 240805B: Global MASTER-Net observations report
  45. GRB 240805B: JinShan optical upper limits
  46. EP240801a: BTA BVRI photometry
  47. Fermi GRB 240805A: Global MASTER-Net observations report
  48. Swift GRB 240805A: Global MASTER-Net observations report
  49. Fermi Gamma-ray Burst Monitor trigger 744558410/240805574 is not a GRB
  50. GRB 240805A: Swift-XRT refined Analysis
  51. EP240804a: GSP detects optical candidate counterpart
  52. GRB 240805B: Swift detection of a burst
  53. GRB 240805A: Fermi-LAT detection
  54. GRB 240805A: INTEGRAL spectral analysis
  55. EP240801a: Continued optical observations at ZTSh (CraO)
  56. EP240804a: VLT/X-shooter spectroscopic redshift
  57. EP240804a: LCOGT optical counterpart detection
  58. GRB 240805A: A long GRB detected by INTEGRAL
  59. EP-WXT trigger 00109017646 is not a real source
  60. EP240804a: NOT optical counterpart detection
  61. EP240804a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  62. EP240802a: correction of EP-WXT trigger time in GCN 37019
  63. GRB 240805A: Swift detection of a burst
  64. GRB 240805A: Fermi GBM Final Real-time Localization
  65. Fermi GRB 240804A: Global MASTER-Net observations report
  66. EP240802a: Montarrenti Observatory optical upper limit
  67. GRB 240804A: Fermi GBM Final Real-time Localization
  68. Fermi trigger No 744459130: Global MASTER-Net observations report
  69. IPN triangulation of GRB 240802A / EP 240802a
  70. Fermi Gamma-ray Burst Monitor trigger 744459130/240804425 is not a GRB
  71. EP240801a: Osservatorio Astronomico Nastro Verde upper limit
  72. EP240802A: Bassano Bresciano Observatory upper limit
  73. GRB 240802A: SVOM/GRM observation
  74. EP240802a: Time coincidence with GRB 240802A and optical upper limits with Kinder observations
  75. Fermi trigger No 744278264: Global MASTER-Net observations report
  76. EP240802a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  77. GRB 240802A: AstroSat CZTI detection of a long burst
  78. EP240801a: further SAO RAS optical observations
  79. EP240801a: optical observations at CrAO and AbAO
  80. EP240801a: GRANDMA and Kilonova-Catcher optical observations
  81. EP240801a: Leavitt Observatory optical observations
  82. EP240801a: GTC spectroscopy and absorption redshift
  83. EP240801a: SAO RAS optical observations
  84. GRB 240801B: AstroSat CZTI Updated classification - likely a solar flare
  85. EP240801a: JinShan optical observations
  86. GRB 240727C: SVOM/GRM observation
  87. EP240801a: NOT optical observations
  88. EP240801a: follow-up observation with LCOGT
  89. Fermi GBM trigger 744179961 / 240801194 can not be confirmed as a GRB
  90. GRB 240730A: Swift-BAT refined analysis
  91. EP240801a: GSP follow-up observations of the candidate counterpart
  92. Fermi trigger No 744204856: Global MASTER-Net observations report
  93. EP240801a: Kinder follow-up observations of the candidate counterpart
  94. EP240708a: Kinder follow-up observations of the candidate counterpart (duplicate submission of GCN 37002)
  95. EP240801a: KAIT optical counterpart observations
  96. EP240801a: GMG observation
  97. EP240801a: TRT optical counterpart detection
  98. EP240801a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  99. GRB 240801B: AstroSat CZTI detection of a bright long burst
  100. Fermi GRB 240801A: Global MASTER-Net observations report

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