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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. Fermi trigger No 744761058: Global MASTER-Net observations report
  2. EP240807a/GRB 240807A: EP-FXT detection of the X-ray emission
  3. S240807h: Identification of a GW compact binary merger candidate
  4. EP-WXT trigger 01709018832: KAIT optical observations of the star flare
  5. EP240802a/GRB240802A: KAIT optical upper limit
  6. GRB 240720B: VZLUSAT-2 detection
  7. GRB 240710A: VZLUSAT-2 detection
  8. EP240806A: Liverpool Telescope optical follow-up observations
  9. The EP-WXT trigger 01709018832 on August 7th is likely a flaring star
  10. GRB 240807A: Fermi GBM Final Localization
  11. EP240807a: EP-WXT detection of a fast X-ray transient
  12. EP240806a: Gemini North-GMOS spectroscopic redshift of z = 2.818
  13. GRB 240805B: GIT optical upper limit
  14. EP240806a: KAIT optical observations
  15. GRB 240805B: Swift-BAT refined analysis
  16. GRB 240805A: Swift-BAT refined analysis
  17. Fermi trigger No 744629911: Global MASTER-Net observations report
  18. EP240804a (GRB 240804B): NOT optical observations
  19. EP240806a: LCOGT optical counterpart detection
  20. Konus-Wind detection of GRB 240802A (EP240802a)
  21. Improved IPN triangulation of GRB 240802A / EP 240802a
  22. Konus-Wind detection of GRB 240805A
  23. GRB 240805B Bassano Bresciano Observatory upper limit
  24. GRB240805A: Fermi GBM Observation
  25. GRB 240805B: JinShan optical afterglow detection
  26. GRB 240804B/EP240804a: Correction to the GRB name in GCN 37071
  27. GRB 240805B: AbAO, CrAO, and Terskol optical upper limits
  28. Konus-Wind detection of GRB 240804B (a counterpart of EP240804a)
  29. Fermi Gamma-ray Burst Monitor trigger 240806402/744629911 is not a GRB
  30. EP240806a: EP-FXT detection of the X-ray emission
  31. GRB 240626B: VZLUSAT-2 detection
  32. GRB 240624B: VZLUSAT-2 detection
  33. GRB 240619C: VZLUSAT-2 detection
  34. EP 240806A: LCO optical observations
  35. EP240806a: GSP optical counterpart detection
  36. EP240806a: EP-WXT detection of a fast X-ray transient
  37. GRB 240805B: Optical detection with 1.6m Mephisto
  38. EP240804a: BOOTES-6/DPRT optical detection
  39. GRB 240805B: NUTTelA-TAO / BSTI Optical Limits
  40. GRB 240805B: Swift-XRT refined Analysis
  41. Fermi trigger No 744544656: Global MASTER-Net observations report
  42. GRB 240805B: Swift/UVOT Upper Limits
  43. GRB 240805A: Swift/UVOT Upper Limits
  44. GRB 240805B: BTA optical afterglow candidate
  45. GRB 240805A: SVOM/GRM observation
  46. GRB 240805B: Enhanced Swift-XRT position
  47. GRB 240805B: LCOGT Optical Upper Limits
  48. Swift GRB 240805B: Global MASTER-Net observations report
  49. GRB 240805B: JinShan optical upper limits
  50. EP240801a: BTA BVRI photometry
  51. Fermi GRB 240805A: Global MASTER-Net observations report
  52. Swift GRB 240805A: Global MASTER-Net observations report
  53. Fermi Gamma-ray Burst Monitor trigger 744558410/240805574 is not a GRB
  54. GRB 240805A: Swift-XRT refined Analysis
  55. EP240804a: GSP detects optical candidate counterpart
  56. GRB 240805B: Swift detection of a burst
  57. GRB 240805A: Fermi-LAT detection
  58. GRB 240805A: INTEGRAL spectral analysis
  59. EP240801a: Continued optical observations at ZTSh (CraO)
  60. EP240804a: VLT/X-shooter spectroscopic redshift
  61. EP240804a: LCOGT optical counterpart detection
  62. GRB 240805A: A long GRB detected by INTEGRAL
  63. EP-WXT trigger 00109017646 is not a real source
  64. EP240804a: NOT optical counterpart detection
  65. EP240804a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  66. EP240802a: correction of EP-WXT trigger time in GCN 37019
  67. GRB 240805A: Swift detection of a burst
  68. GRB 240805A: Fermi GBM Final Real-time Localization
  69. Fermi GRB 240804A: Global MASTER-Net observations report
  70. EP240802a: Montarrenti Observatory optical upper limit
  71. GRB 240804A: Fermi GBM Final Real-time Localization
  72. Fermi trigger No 744459130: Global MASTER-Net observations report
  73. IPN triangulation of GRB 240802A / EP 240802a
  74. Fermi Gamma-ray Burst Monitor trigger 744459130/240804425 is not a GRB
  75. EP240801a: Osservatorio Astronomico Nastro Verde upper limit
  76. EP240802A: Bassano Bresciano Observatory upper limit
  77. GRB 240802A: SVOM/GRM observation
  78. EP240802a: Time coincidence with GRB 240802A and optical upper limits with Kinder observations
  79. Fermi trigger No 744278264: Global MASTER-Net observations report
  80. EP240802a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  81. GRB 240802A: AstroSat CZTI detection of a long burst
  82. EP240801a: further SAO RAS optical observations
  83. EP240801a: optical observations at CrAO and AbAO
  84. EP240801a: GRANDMA and Kilonova-Catcher optical observations
  85. EP240801a: Leavitt Observatory optical observations
  86. EP240801a: GTC spectroscopy and absorption redshift
  87. EP240801a: SAO RAS optical observations
  88. GRB 240801B: AstroSat CZTI Updated classification - likely a solar flare
  89. EP240801a: JinShan optical observations
  90. GRB 240727C: SVOM/GRM observation
  91. EP240801a: NOT optical observations
  92. EP240801a: follow-up observation with LCOGT
  93. Fermi GBM trigger 744179961 / 240801194 can not be confirmed as a GRB
  94. GRB 240730A: Swift-BAT refined analysis
  95. EP240801a: GSP follow-up observations of the candidate counterpart
  96. Fermi trigger No 744204856: Global MASTER-Net observations report
  97. EP240801a: Kinder follow-up observations of the candidate counterpart
  98. EP240708a: Kinder follow-up observations of the candidate counterpart (duplicate submission of GCN 37002)
  99. EP240801a: KAIT optical counterpart observations
  100. EP240801a: GMG observation

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