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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. GRB 240805B: Swift-XRT refined Analysis
  2. Fermi trigger No 744544656: Global MASTER-Net observations report
  3. GRB 240805B: Swift/UVOT Upper Limits
  4. GRB 240805A: Swift/UVOT Upper Limits
  5. GRB 240805B: BTA optical afterglow candidate
  6. GRB 240805A: SVOM/GRM observation
  7. GRB 240805B: Enhanced Swift-XRT position
  8. GRB 240805B: LCOGT Optical Upper Limits
  9. Swift GRB 240805B: Global MASTER-Net observations report
  10. GRB 240805B: JinShan optical upper limits
  11. EP240801a: BTA BVRI photometry
  12. Fermi GRB 240805A: Global MASTER-Net observations report
  13. Swift GRB 240805A: Global MASTER-Net observations report
  14. Fermi Gamma-ray Burst Monitor trigger 744558410/240805574 is not a GRB
  15. GRB 240805A: Swift-XRT refined Analysis
  16. EP240804a: GSP detects optical candidate counterpart
  17. GRB 240805B: Swift detection of a burst
  18. GRB 240805A: Fermi-LAT detection
  19. GRB 240805A: INTEGRAL spectral analysis
  20. EP240801a: Continued optical observations at ZTSh (CraO)
  21. EP240804a: VLT/X-shooter spectroscopic redshift
  22. EP240804a: LCOGT optical counterpart detection
  23. GRB 240805A: A long GRB detected by INTEGRAL
  24. EP-WXT trigger 00109017646 is not a real source
  25. EP240804a: NOT optical counterpart detection
  26. EP240804a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  27. EP240802a: correction of EP-WXT trigger time in GCN 37019
  28. GRB 240805A: Swift detection of a burst
  29. GRB 240805A: Fermi GBM Final Real-time Localization
  30. Fermi GRB 240804A: Global MASTER-Net observations report
  31. EP240802a: Montarrenti Observatory optical upper limit
  32. GRB 240804A: Fermi GBM Final Real-time Localization
  33. Fermi trigger No 744459130: Global MASTER-Net observations report
  34. IPN triangulation of GRB 240802A / EP 240802a
  35. Fermi Gamma-ray Burst Monitor trigger 744459130/240804425 is not a GRB
  36. EP240801a: Osservatorio Astronomico Nastro Verde upper limit
  37. EP240802A: Bassano Bresciano Observatory upper limit
  38. GRB 240802A: SVOM/GRM observation
  39. EP240802a: Time coincidence with GRB 240802A and optical upper limits with Kinder observations
  40. Fermi trigger No 744278264: Global MASTER-Net observations report
  41. EP240802a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  42. GRB 240802A: AstroSat CZTI detection of a long burst
  43. EP240801a: further SAO RAS optical observations
  44. EP240801a: optical observations at CrAO and AbAO
  45. EP240801a: GRANDMA and Kilonova-Catcher optical observations
  46. EP240801a: Leavitt Observatory optical observations
  47. EP240801a: GTC spectroscopy and absorption redshift
  48. EP240801a: SAO RAS optical observations
  49. GRB 240801B: AstroSat CZTI Updated classification - likely a solar flare
  50. EP240801a: JinShan optical observations
  51. GRB 240727C: SVOM/GRM observation
  52. EP240801a: NOT optical observations
  53. EP240801a: follow-up observation with LCOGT
  54. Fermi GBM trigger 744179961 / 240801194 can not be confirmed as a GRB
  55. GRB 240730A: Swift-BAT refined analysis
  56. EP240801a: GSP follow-up observations of the candidate counterpart
  57. Fermi trigger No 744204856: Global MASTER-Net observations report
  58. EP240801a: Kinder follow-up observations of the candidate counterpart
  59. EP240708a: Kinder follow-up observations of the candidate counterpart (duplicate submission of GCN 37002)
  60. EP240801a: KAIT optical counterpart observations
  61. EP240801a: GMG observation
  62. EP240801a: TRT optical counterpart detection
  63. EP240801a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  64. GRB 240801B: AstroSat CZTI detection of a bright long burst
  65. Fermi GRB 240801A: Global MASTER-Net observations report
  66. GRB 240801A: Fermi GBM Final Real-time Localization
  67. GRB 240730C: AstroSat CZTI detection of a long burst
  68. GRB 240731A: Fermi GBM Final Localization
  69. Fermi trigger No 744128417: Global MASTER-Net observations report
  70. Fermi trigger No 744083370: Global MASTER-Net observations report
  71. GRB 240731A: AstroSat CZTI detection
  72. GRB 240730A: Osservatorio Astronomico Nastro Verde upper limit
  73. GRB240730A: BOOTES-5/JGT early optical upper limit
  74. Fermi Gamma-ray Burst Monitor trigger 744061103/240730818 is not a GRB
  75. Fermi GRB 240730B: Global MASTER-Net observations report
  76. GRB 240730B: Fermi GBM Final Real-time Localization
  77. Swift GRB 240730A: Global MASTER-Net observations report
  78. GRB 240730A: Swift-XRT refined Analysis
  79. GRB 240715A: Swift-XRT afterglow detection
  80. GRB 240730A: KAIT Optical Upper Limit
  81. GRB 240727C: GRBAlpha detection
  82. GRB 240730A: Swift/UVOT Upper Limits
  83. GRB 240730A: Enhanced Swift-XRT position
  84. GRB 240730A: Swift detection of a burst
  85. Fermi trigger No 743953682: Global MASTER-Net observations report
  86. GRB 240727A: Swift-BAT refined analysis
  87. Fermi Gamma-ray Burst Monitor trigger 743953682/240729575 is not a GRB
  88. LIGO/Virgo/KAGRA S240615dg: GRAWITA wide-field optical observations
  89. GRB 240727A: observations of optical counterpart.
  90. GRB 240727B: Swift-XRT observations
  91. Fermi GRB 240727A: Global MASTER-Net observations report
  92. GRB 240727A: Swift/UVOT detection
  93. Fermi trigger No 743868421: Global MASTER-Net observations report
  94. Fermi Gamma-ray Burst Monitor trigger 743868421/240728588 is not a GRB
  95. GRB 240727A: Correction to time in GCN36960
  96. GRB 240727A: Osservatorio Astronomico Nastro Verde upper limit
  97. EP-WXT trigger 01709002661 is not a real source
  98. GRB 240727A: NOT optical observation
  99. GRB 240727A: JinShan optical upper limits
  100. GRB 240727A Bassano Bresciano Observatory upper limit

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