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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"

28050 results found.

  1. GRB 230802A: Swift detection of a burst
  2. IceCube-230724A: JCMT/SCUBA-2 submm observations
  3. IceCube-230707A: JCMT/SCUBA-2 submm observations
  4. LIGO/Virgo/KAGRA S230731an: Upper limits from Swift/BAT-GUANO
  5. LIGO/Virgo/KAGRA S230731an: AstroSat CZTI non-detection and upper limits
  6. LIGO/Virgo/KAGRA S230731an: Updated Sky Localization and EM Bright Classification, and Correction to Source Classification
  7. LIGO/Virgo/KAGRA S230731an: Coverage and upper limits from MAXI/GSC observations
  8. LIGO/Virgo/KAGRA S230731an: Identification of a GW compact binary merger candidate
  9. LIGO/Virgo/KAGRA S230729z: Updated Sky localization
  10. GRB 230723A: Detection of candidate millimeter-band radiation by SPT-3G
  11. Fermi trigger No 712390645: Global MASTER-Net observations report
  12. GRB 230728A: Swift-BAT refined analysis
  13. Fermi-LAT gamma-ray observations of IceCube-230727A
  14. GRB 230723B: Swift-BAT refined analysis
  15. Fermi trigger No 712306969: Global MASTER-Net observations report
  16. GRB 230723B: MITSuME Ishigaki optical observation
  17. LIGO/Virgo/KAGRA S230729z: Identification of a GW compact binary merger candidate
  18. IceCube-230727A: Upper limits from a search for additional neutrino events in IceCube
  19. GRB 230728A: BOOTES-1 optical upper limit
  20. GRB 230728A: Fermi GBM Observation
  21. GRB 230728A: LCOGT Optical Upper Limit
  22. GRB 230728A: Swift/UVOT Upper Limits
  23. GRB 230728A: Swift-XRT refined Analysis
  24. GRB 230728A: Enhanced Swift-XRT position
  25. GRB 230728A: NOT optical observations and possible host galaxy
  26. GRB 230728A: Swift detection of a burst
  27. GRB 230727A: Swift/BAT-GUANO detection of a burst
  28. Fermi-LAT gamma-ray observations of IceCube-230725A
  29. Fermi-LAT gamma-ray observations of IceCube-230724A
  30. IceCube-230725A: Upper limits from a search for additional neutrino events in IceCube
  31. IceCube-230724A: Upper limits from a search for additional neutrino events in IceCube
  32. GRB 230723B: Further CAHA observations and host galaxy detection
  33. LIGO/Virgo/KAGRA S230726a: Updated Sky localization
  34. GRB 230723B: MITSuME Akeno optical afterglow candidate detection
  35. LIGO/Virgo/KAGRA S230726b: one counterpart neutrino candidate from IceCube neutrino searches
  36. LIGO/Virgo/KAGRA S230726a: Identification of a GW compact binary merger candidate
  37. GRB 230723B: GAD Observatory, La Spezia, Italy upper limit
  38. GRB 230723B: Leavitt Observatory upper limit
  39. GRB 230723B: Osservatorio Astronomico Nastro Verde upper limit
  40. GRB 230723B: Montarrenti Observatory upper limit
  41. GRB 230723B: Optical afterglow candidate from CAHA
  42. GRB 230723B: Bassano Bresciano Observatory upper limit
  43. GRB 230723B: Fermi GBM observation
  44. GRB 230723B: Swift-XRT refined Analysis
  45. GRB 230723B: non-detections from Observatoire de Haute-Provence
  46. LIGO/Virgo/KAGRA S230723ac: Updated Sky localization
  47. GRB 230723B: Optical limit from CAHA
  48. GRB 230723B: Swift/UVOT Upper Limits
  49. GRB 230723B: Swift-XRT observations
  50. LIGO/Virgo/KAGRA S230723ac: Identification of a GW compact binary merger candidate
  51. GRB 230723B: Swift detection of a burst
  52. IPN triangulation of GRB 230715D
  53. Swift Trigger 1180055 is not a GRB
  54. LIGO/Virgo/KAGRA S230708z: Updated Sky localization
  55. IceCube-230707A : MAXI upper limit and NICER follow-up observation of Swift J1753.5-0127
  56. LIGO/Virgo/KAGRA S230709bi: Updated Sky localization
  57. LIGO/Virgo/KAGRA S230708t: Updated Sky localization
  58. GRB 230709C: Swift/BAT-GUANO detection of a short burst outside the coded FOV
  59. IceCube-230708A: Upper limits from Swift/BAT-GUANO
  60. GRB 230709C: GRBAlpha detection
  61. GRB 230707B: Fermi GBM Observation
  62. LIGO/Virgo/KAGRA S230708z: Identification of a GW compact binary merger candidate
  63. LIGO/Virgo/KAGRA S230708t: Identification of a GW compact binary merger candidate
  64. IceCube-230707A: No candidates detected by Swift-XRT
  65. LIGO/Virgo/KAGRA S230708cf: Updated Sky localization
  66. GRB 230703A detected with multiple GRID detectors
  67. GRB 230709C: BALROG localization (Fermi Trigger 710617111 / GRB 230709735)
  68. LIGO/Virgo/KAGRA S230707ai: Updated Sky localization
  69. Fermi-LAT gamma-ray observations of IceCube-230708A
  70. Fermi-LAT gamma-ray observations of IceCube-230707B
  71. Fermi-LAT gamma-ray observations of IceCube-230707A
  72. LIGO/Virgo/KAGRA S230630am: Updated Sky localization
  73. LIGO/Virgo/KAGRA S230630am: Updated Sky localization
  74. GRB 230709B: BALROG localization (Fermi Trigger 710614579 / GRB 230709706)
  75. IceCube-230708A: Upper limits from a search for additional neutrino events in IceCube
  76. IceCube-230707B: Upper limits from a search for additional neutrino events in IceCube
  77. IceCube-230707A: Upper limits from a search for additional neutrino events in IceCube
  78. LIGO/Virgo/KAGRA S230709bi: Identification of a GW compact binary merger candidate
  79. LIGO/Virgo/KAGRA S230708cf: Identification of a GW compact binary merger candidate
  80. GRB 230707B: Swift/BAT-GUANO detection of a burst outside the coded FOV
  81. GRB 230707A: Swift-XRT observations
  82. GRB 230707A: Fermi GBM Detection
  83. LIGO/Virgo/KAGRA S230707ai: Identification of a GW compact binary merger candidate
  84. GRB 230707A: Swift/BAT-GUANO arcminute localization of a burst
  85. LIGO/Virgo/KAGRA S230706ah: Updated Sky localization
  86. LIGO/Virgo/KAGRA S230704f: Updated Sky localization
  87. LIGO/Virgo/KAGRA S230630bq: Updated Sky localization
  88. LIGO/Virgo/KAGRA S230702an: Updated Sky localization
  89. LIGO/Virgo/KAGRA S230529ay: Updated Sky localization and EM Bright Classification
  90. LIGO/Virgo/KAGRA S230706ah: Identification of a GW compact binary merger candidate
  91. LIGO/Virgo/KAGRA S230627c: GECKO optical follow-up observations of host galaxy candidates and ZTF23aaptsuy/AT2023lxu
  92. ZTF23aaoohpy/AT2023lcr: AMI-LA radio detection
  93. Fermi trigger No 710117592: Global MASTER-Net observations report
  94. GRB 230626A: VZLUSAT-2 detection
  95. LVK S230619bd/GBM-230619: Upper limits from a two-week IceCube neutrino search
  96. GRB 230328B: LBT detection of the likely host galaxy
  97. LIGO/Virgo/KAGRA S230704f: Identification of a GW compact binary merger candidate
  98. GRB 230701B: AstroSat CZTI detection
  99. LIGO/Virgo/KAGRA S230627c: observations of ZTF23aaptsuy/AT2023lx in AbAO observatory
  100. LIGO/Virgo/KAGRA S230702an: Identification of a GW compact binary merger candidate

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