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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 230911C: Swift detection of a burst
  2. Fermi GRB 230911B: Global MASTER-Net observations report
  3. GRB 230911B: Fermi GBM Final Real-time Localization
  4. GRB 230911A: Fermi GBM Final Real-time Localization
  5. GRB 230906A: BlackGEM upper limits
  6. GRB 230903A: TESS observations of optical emission
  7. GRB 230906A: AstroSat CZTI detection
  8. GRB 230910A: Fermi GBM Final Real-time Localization
  9. GRB 230908A: GRBAlpha detection
  10. LIGO/Virgo/KAGRA S230908b: one counterpart neutrino candidate from IceCube neutrino searches
  11. GRB 230908A: AstroSat CZTI detection
  12. Glowbug gamma-ray detection GRB 230905B
  13. GRB 230906A: Swift/UVOT Upper Limits
  14. GRID detection of GRB 230827A
  15. GRB 230818A: radio observation with the VLA
  16. GRB 230205A: LBT spectroscopy of two host galaxy candidates
  17. GRB 230906A: Swift-XRT observations
  18. Konus-Wind detection of GRB 230906A (short)
  19. IPN triangulation of GRB 230906A (short)
  20. GRB 230906A: Swift ToO observations
  21. GRB 230905B: AstroSat CZTI detection
  22. Fermi GRB 230906A: Global MASTER-Net observations report
  23. Swift Attitude Control Affecting Some UVOT Images
  24. GRB 230812B: Chandra late-time detection of the X-ray afterglow
  25. GRB 230906A: Fermi GBM Final Localizationn
  26. GRB 230905B: GECAM-C detection of a long burst
  27. LIGO/Virgo/KAGRA S230904n: Updated Sky localization and EM Bright Classification
  28. GRB 230905A: Fermi GBM Final Real-time Localization
  29. LIGO/Virgo/KAGRA S230819ax: Correction to PROB_BBH and PROB_TERRES probabilities
  30. GRB 230903A: Swift-XRT refined Analysis
  31. GRB 230903A: Enhanced Swift-XRT position
  32. GRB 230903A: VLT/X-shooter optical observations
  33. GRB 230903A: Swift-BAT refined analysis
  34. GRB 230904C: Fermi GBM Final Localization
  35. Fermi trigger No 715552087: Global MASTER-Net observations report
  36. Fermi trigger No 715429986: Global MASTER-Net observations report
  37. Fermi GRB 230903A: Global MASTER-Net observations report
  38. GRB 230903A: Fermi GBM detection
  39. GRB 230904B is not a GRB
  40. LIGO/Virgo/KAGRA S230904n: 1 counterpart neutrino candidate from IceCube neutrino searches
  41. GRB 230904B: BALROG localization (Fermi Trigger 715526984 / GRB 230904562)
  42. Fermi GRB 230904A: Global MASTER-Net observations report
  43. GRB 230904A: Fermi GBM Final Real-time Localization
  44. LIGO/Virgo/KAGRA S230904n: Identification of a GW compact binary merger candidate
  45. GRB 230903A: LCOGT Optical Upper Limits
  46. GRB 230903A: Swift detection of a burst
  47. Swift GRB230903.72: Global MASTER-Net observations report
  48. GRB 230903A: Fermi GBM Final Real-time Localization
  49. Integral GRB230902.00: Global MASTER-Net observations report
  50. LIGO/Virgo/KAGRA S230831e: Updated Sky localization
  51. LIGO/Virgo/KAGRA S230831e: Identification of a GW compact binary merger candidate
  52. GRB 230827B: Glowbug gamma-ray detection
  53. GRB 230827A: Glowbug gamma-ray detection
  54. GRB 230826A: Glowbug gamma-ray detection
  55. GRB 230827B: Swift-XRT afterglow detection
  56. LIGO/Virgo/KAGRA S230715bw: Reissue of Retraction of GW compact binary merger candidate
  57. LIGO/Virgo/KAGRA S230830b: Retraction of GW compact binary merger candidate
  58. LIGO/Virgo/KAGRA S230820bq: Updated Sky localization
  59. GRB 230812B: Spectroscopic detection of the associated SN 2023pel.
  60. GRB 230827B: Swift ToO observations
  61. LIGO/Virgo/KAGRA S230814ah: Updated Sky localization
  62. GRB 230827A: Fermi GBM Observation
  63. GRB 230827B: CALET Gamma-Ray Burst Monitor detection
  64. GRB 230826A: Swift-BAT refined analysis
  65. GRB 230828A: AstroSat CZTI detection
  66. GRB 230828A: GRBAlpha detection
  67. Swift Trigger 1188089 is not a GRB
  68. GRB 230827A: VZLUSAT-2 detection
  69. GRB 230827A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  70. GRB 230826A: VZLUSAT-2 detection
  71. GRB 230827B: VZLUSAT-2 detection
  72. GRB 230827B / GRB 230827256: Fermi GBM Observation
  73. GRB 230827A: GRBAlpha detection
  74. Subject: GRB230826A: Swift/UVOT upper limits
  75. GRB 230827A: BALROG localization (Fermi Trigger / GRB 230827762)
  76. Fermi trigger No 714809315: Global MASTER-Net observations report
  77. GRB 230827.256: AKO Optical follow-up of ZTF23abaanxz (AT 2023qxj)
  78. Fermi GRB 230827A: Global MASTER-Net observations report
  79. Swift J1727.8-1613 (GRB 230824A): Osservatorio Astronomico "Nastro Verde" optical observations
  80. GRB 230827.256 : GIT optical follow-up of ZTF23abaanxz/AT2023qxj
  81. GRB 230827A: Fermi GBM Final Real-time Localization
  82. AT 2023qxj: ZTF discovery of the likely afterglow of Fermi GRB 230827256
  83. Swift J1727.8-1613 (GRB 230824A): Montarrenti Observatory photometric observations
  84. GRB 230826A: GRBAlpha detection
  85. GRB 230826A: Fermi GBM Observation
  86. Swift J1727.8-1613 (GRB 230824A): Leavitt Observatory optical observations
  87. GRB 230826A: Enhanced Swift-XRT position
  88. GRB 230826A: Swift-XRT refined Analysis
  89. GRB 230826A: Mondy optical observations
  90. Swift J1727.8-1613 (GRB 230824A): GAD Observatory La Spezia - optical observations
  91. GRB 230826A: Swift detection of a burst
  92. GRB 230826A: Fermi GBM Final Real-time Localization
  93. Swift GRB230826.81: Global MASTER-Net observations report
  94. Swift J1727.8-1613 (GRB 230824A): Bassano Bresciano Observatory optical observations
  95. GRB 230824A: AKO Photometric Follow-up Observations
  96. GRB 230818B: CALET Gamma-Ray Burst Monitor detection
  97. LIGO/Virgo/KAGRA S230825k: Upper limits from Swift/BAT-GUANO
  98. Swift GRB230825.85: Global MASTER-Net observations report
  99. Trigger 1187225: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  100. Swift J1727.8-1613 (GRB 230824A): Skynet Optical Observations

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