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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. S240807h: Identification of a GW compact binary merger candidate
  2. EP-WXT trigger 01709018832: KAIT optical observations of the star flare
  3. EP240802a/GRB240802A: KAIT optical upper limit
  4. GRB 240720B: VZLUSAT-2 detection
  5. GRB 240710A: VZLUSAT-2 detection
  6. EP240806A: Liverpool Telescope optical follow-up observations
  7. The EP-WXT trigger 01709018832 on August 7th is likely a flaring star
  8. GRB 240807A: Fermi GBM Final Localization
  9. EP240807a: EP-WXT detection of a fast X-ray transient
  10. EP240806a: Gemini North-GMOS spectroscopic redshift of z = 2.818
  11. GRB 240805B: GIT optical upper limit
  12. EP240806a: KAIT optical observations
  13. GRB 240805B: Swift-BAT refined analysis
  14. GRB 240805A: Swift-BAT refined analysis
  15. Fermi trigger No 744629911: Global MASTER-Net observations report
  16. EP240804a (GRB 240804B): NOT optical observations
  17. EP240806a: LCOGT optical counterpart detection
  18. Konus-Wind detection of GRB 240802A (EP240802a)
  19. Improved IPN triangulation of GRB 240802A / EP 240802a
  20. Konus-Wind detection of GRB 240805A
  21. GRB 240805B Bassano Bresciano Observatory upper limit
  22. GRB240805A: Fermi GBM Observation
  23. GRB 240805B: JinShan optical afterglow detection
  24. GRB 240804B/EP240804a: Correction to the GRB name in GCN 37071
  25. GRB 240805B: AbAO, CrAO, and Terskol optical upper limits
  26. Konus-Wind detection of GRB 240804B (a counterpart of EP240804a)
  27. Fermi Gamma-ray Burst Monitor trigger 240806402/744629911 is not a GRB
  28. EP240806a: EP-FXT detection of the X-ray emission
  29. GRB 240626B: VZLUSAT-2 detection
  30. GRB 240624B: VZLUSAT-2 detection
  31. GRB 240619C: VZLUSAT-2 detection
  32. EP 240806A: LCO optical observations
  33. EP240806a: GSP optical counterpart detection
  34. EP240806a: EP-WXT detection of a fast X-ray transient
  35. GRB 240805B: Optical detection with 1.6m Mephisto
  36. EP240804a: BOOTES-6/DPRT optical detection
  37. GRB 240805B: NUTTelA-TAO / BSTI Optical Limits
  38. GRB 240805B: Swift-XRT refined Analysis
  39. Fermi trigger No 744544656: Global MASTER-Net observations report
  40. GRB 240805B: Swift/UVOT Upper Limits
  41. GRB 240805A: Swift/UVOT Upper Limits
  42. GRB 240805B: BTA optical afterglow candidate
  43. GRB 240805A: SVOM/GRM observation
  44. GRB 240805B: Enhanced Swift-XRT position
  45. GRB 240805B: LCOGT Optical Upper Limits
  46. Swift GRB 240805B: Global MASTER-Net observations report
  47. GRB 240805B: JinShan optical upper limits
  48. EP240801a: BTA BVRI photometry
  49. Fermi GRB 240805A: Global MASTER-Net observations report
  50. Swift GRB 240805A: Global MASTER-Net observations report
  51. Fermi Gamma-ray Burst Monitor trigger 744558410/240805574 is not a GRB
  52. GRB 240805A: Swift-XRT refined Analysis
  53. EP240804a: GSP detects optical candidate counterpart
  54. GRB 240805B: Swift detection of a burst
  55. GRB 240805A: Fermi-LAT detection
  56. GRB 240805A: INTEGRAL spectral analysis
  57. EP240801a: Continued optical observations at ZTSh (CraO)
  58. EP240804a: VLT/X-shooter spectroscopic redshift
  59. EP240804a: LCOGT optical counterpart detection
  60. GRB 240805A: A long GRB detected by INTEGRAL
  61. EP-WXT trigger 00109017646 is not a real source
  62. EP240804a: NOT optical counterpart detection
  63. EP240804a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  64. EP240802a: correction of EP-WXT trigger time in GCN 37019
  65. GRB 240805A: Swift detection of a burst
  66. GRB 240805A: Fermi GBM Final Real-time Localization
  67. Fermi GRB 240804A: Global MASTER-Net observations report
  68. EP240802a: Montarrenti Observatory optical upper limit
  69. GRB 240804A: Fermi GBM Final Real-time Localization
  70. Fermi trigger No 744459130: Global MASTER-Net observations report
  71. IPN triangulation of GRB 240802A / EP 240802a
  72. Fermi Gamma-ray Burst Monitor trigger 744459130/240804425 is not a GRB
  73. EP240801a: Osservatorio Astronomico Nastro Verde upper limit
  74. EP240802A: Bassano Bresciano Observatory upper limit
  75. GRB 240802A: SVOM/GRM observation
  76. EP240802a: Time coincidence with GRB 240802A and optical upper limits with Kinder observations
  77. Fermi trigger No 744278264: Global MASTER-Net observations report
  78. EP240802a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  79. GRB 240802A: AstroSat CZTI detection of a long burst
  80. EP240801a: further SAO RAS optical observations
  81. EP240801a: optical observations at CrAO and AbAO
  82. EP240801a: GRANDMA and Kilonova-Catcher optical observations
  83. EP240801a: Leavitt Observatory optical observations
  84. EP240801a: GTC spectroscopy and absorption redshift
  85. EP240801a: SAO RAS optical observations
  86. GRB 240801B: AstroSat CZTI Updated classification - likely a solar flare
  87. EP240801a: JinShan optical observations
  88. GRB 240727C: SVOM/GRM observation
  89. EP240801a: NOT optical observations
  90. EP240801a: follow-up observation with LCOGT
  91. Fermi GBM trigger 744179961 / 240801194 can not be confirmed as a GRB
  92. GRB 240730A: Swift-BAT refined analysis
  93. EP240801a: GSP follow-up observations of the candidate counterpart
  94. Fermi trigger No 744204856: Global MASTER-Net observations report
  95. EP240801a: Kinder follow-up observations of the candidate counterpart
  96. EP240708a: Kinder follow-up observations of the candidate counterpart (duplicate submission of GCN 37002)
  97. EP240801a: KAIT optical counterpart observations
  98. EP240801a: GMG observation
  99. EP240801a: TRT optical counterpart detection
  100. EP240801a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient

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