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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. EP241101a NUTTelA-TAO / BSTI Measurements 2024-11-02
  2. GRB 241104A : Detection and localization by SVOM/ECLAIRs
  3. GRB 240821A: further radio observations with the VLA
  4. Fermi GRB 241104A: Global MASTER-Net observations report
  5. GRB 241104A: Fermi GBM Final Real-time Localization
  6. GRB 241030A: GRBAlpha detection
  7. EP241101a: EP-FXT observations update
  8. EP241103a: GIT optical upper limit
  9. EP241021a: OHP/T193 further optical observations
  10. LIGO/Virgo/KAGRA S241104a: Retraction of GW compact binary merger candidate
  11. Fermi trigger No 752365806: Global MASTER-Net observations report
  12. LIGO/Virgo/KAGRA S241102br: OHP/T193 optical observations
  13. LIGO/Virgo/KAGRA S241102cy: Updated Sky localization
  14. EP241103a: GOTO optical upper limit
  15. LIGO/Virgo/KAGRA S241102br: Updated Sky localization
  16. EP241101a: Possible detection of an optical counterpart with FTW
  17. EP241103a: Swift XRT detection and improved X-ray position
  18. EP241021a: continued SOAR observations
  19. EP241101a: Optical upper limits with Kinder observations
  20. EP241101a: OHP/T193 optical observations
  21. EP241103a: Gemini optical limits
  22. EP241103a: EP observation update
  23. LIGO/Virgo/KAGRA S241102br: MASTER observations and OT detection
  24. LIGO/Virgo/KAGRA S241102br: EP-WXT X-ray follow-up and flux limits
  25. GRB 241030A: Swift-UVOT observations of the optical prompt flare
  26. EP241103a: GSP optical upper limit
  27. EP241103A: LCO optical observations
  28. EP241103a: Global MASTER-Net observations report
  29. EP241103a: an X-ray transient detected by Einstein Probe
  30. GRB 241030A: Rapid release of TESS data.
  31. EP241101a: Global MASTER-Net observations report
  32. GRB 241029A: GRBAlpha detection
  33. EP241101a: BOOTES-7 optical upper limit
  34. LIGO/Virgo/KAGRA S241101ee: Updated Sky localization
  35. S241102cy: Identification of a GW compact binary merger candidate
  36. LIGO/Virgo/KAGRA S241102br: NED Galaxies in the Localization Volume
  37. LIGO/Virgo/KAGRA S241102br: Identification of a GW compact binary merger candidate
  38. Kinder optical follow-up observations of EP241021a, EP241026b, and EP241030a/GRB241030A
  39. GRB241030A: OHP/T193 optical observations
  40. EP241030a: Futher EP-FXT observation of the X-ray Afterglow of GRB 241030A
  41. EP241101a: EP-WXT detection of a fast X-ray transient
  42. Swift GRB 241101A: Global MASTER-Net observations report
  43. GRB 241101A: FRAM-ORM optical limit
  44. LIGO/Virgo/KAGRA S241101ee: Identification of a GW compact binary merger candidate
  45. GRB 241030A/EP241030a: TNOT observations of the optical counterpart
  46. EP241021a: Upper limit from Konus-Wind observations
  47. GRB 241101A: Swift-BAT refined analysis
  48. GRB 241030A: further SAO RAS optical observations
  49. GRB 241030A: Optical Observations via Virtual Telescope Project
  50. EP241021a: Liverpool Telescope optical follow-up observations
  51. GRB 241030B: Swift-XRT refined Analysis
  52. GRB 241026A: SAO RAS optical observations
  53. GRB 241030A / EP241030a: GMG possible spectroscopic redshift at z ~ 1.4
  54. EP241030a: EP/FXT observation of GRB 241030A X-ray Afterglow
  55. GRB 241101A: Swift detection of a burst
  56. GRB 241030B: NUTTelA-TAO / BSTI Optical Limits (duplicate submission of 38023)
  57. GRB 241030B: NUTTelA-TAO / BSTI Optical Limits
  58. EP241021a: OHP/T193 optical observations
  59. GRB 241030A: Palomar 1-m telescope COSMOS optical observations
  60. GRB 241030B: Montarrenti Observatory optical upper limit
  61. GRB 241030A / EP241030a: FTW Optical and NIR observations of the optical counterpart
  62. EP241026b: Liverpool Telescope optical follow-up
  63. Fermi trigger No 752083996: Global MASTER-Net observations report
  64. GRB 241030A: SAO RAS optical observations
  65. GRB 241030A: Fermi GBM Observation
  66. EP241021a: AMI-LA radio detection
  67. GRB 241030B : GIT optical upper limits
  68. GRB 241030B: LCOGT Optical Upper Limits
  69. GRB 241030B: Swift-BAT refined analysis
  70. GRB 241030A: Swift-BAT refined analysis
  71. GRB 241029A: COLIBRI Detection of the Optical Counterpart
  72. GRB 241030B: Swift/UVOT Detection
  73. EP EP241030a: Global MASTER-Net observations report
  74. GRB 241029A: LCO optical detection
  75. Fermi trigger No 752006065: Global MASTER-Net observations report
  76. GRB 241030B: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.82
  77. Swift GRB241030.77: Global MASTER-Net observations report
  78. GRB 241030B: SVOM/GRM observation
  79. GRB 241030B : MITSuME Akeno optical upper limits
  80. GRB 241030A: COLIBRI Continuing Detection of the Afterglow
  81. GRB 241030B: SVOM/VT optical afterglow observations
  82. GRB 241030B: COLIBRÍ Upper Limits on the Optical Counterpart
  83. EP241030a: EP detection of GRB 241030A X-ray Afterglow
  84. GRB241030B: Fermi GBM Observation
  85. GRB 241030B: BTA observations
  86. GRB 241029A: SVOM/VT optical afterglow observations
  87. GRB 241030A: detection of the bright optical counterpart in ATLAS forced photometry
  88. GRB 241030B: Enhanced Swift-XRT position
  89. GRB 241030B: optical observations from the INAF Asiago Observatory
  90. EP241021a: Swift-UVOT detection
  91. GRB241030B: GRANDMA/TAROT Upper Limit
  92. GRB 241030A: Swift-XRT refined Analysis
  93. GRB 241030B: SAO RAS optical observations
  94. GRB 241030B: AKO Optical Afterglow Detection
  95. GRB 241030B: Nanshan/HMT optical afterglow detection
  96. GRB 241030B: SVOM/ECLAIRs detection of a burst
  97. GRB 241030B: Prompt enhanced Swift-XRT position
  98. Konus-Wind detection of GRB 241030A
  99. GRB 241030B: Swift detection of a burst
  100. GRB 241030B: Fermi GBM Final Real-time Localization

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