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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').

19119 results found.

  1. GRB 241209C: Swift/BAT-GUANO localization skymap of a burst
  2. GRB 241209A: GRANDMA/TAROT upper limit
  3. GRB 241209B: BOOTES-5 optical upper limit
  4. LIGO/Virgo/KAGRA S241102br: continued GRAWITA observations and detection of an optical transient (AT2024adip)
  5. GRB 241209A: REM optical/NIR observations
  6. GRB 241209D: Enhanced Swift-XRT position
  7. GRB 241209D: Swift detection of a burst
  8. GRB 241209A: Enhanced Swift-XRT position
  9. GRB 241114B: cubesat Avion detection
  10. GRB 241209A: VLT optical observations
  11. GRB 241209A: GOTO optical upper limits
  12. GRB 241209B: SVOM/ECLAIRs and GRM detection of a long burst
  13. EP241208a: EP detection of a fast X-ray transient
  14. GRB 241209A: Swift detection of a short burst
  15. GRB 241207B: Swift/BAT-GUANO localization skymap of a short burst
  16. GRB 241206A: DDOTI Upper Limit on the Afterglow
  17. EP241206a: BOOTES Global Network optical limits
  18. EP241206a: EP detection of a fast X-ray transient
  19. GRB 241206A: Swift/BAT-GUANO localization skymap of a burst
  20. GRB 241206B: SVOM/ECLAIRs detection of a long soft transient
  21. EP241201a: 1.6m Mephisto Optical Upper Limits
  22. GRB 241204A: COLIBRÍ Optical Upper Limit
  23. EP241202b: KAIT optical upper limit
  24. GRB 241204A: DDOTI Upper Limits on the Afterglow
  25. GRB 241201A: GRBAlpha detection
  26. GRB 241204A: Fermi-LAT detection
  27. IceCube-241127A: No transient candidates from the Zwicky Transient Facility
  28. EP241202b: Kinder optical counterpart candidate
  29. Konus-Wind detection of GRB 241130A
  30. EP241201a: BOOTES-5 optical upper limit
  31. EP241202b: EP detection of a fast X-ray transient
  32. EP241201a: NOT optical observations
  33. GRB 241128A: Swift/UVOT Upper Limits
  34. GRB 241129A: Swift/BAT-GUANO localization skymap of a burst
  35. EP241201a: Kinder optical counterpart candidate
  36. LIGO/Virgo/KAGRA S241102br: GRAWITA wide-field optical observations
  37. EP241126a: 1.6m Mephisto Optical Upper Limits
  38. LIGO/Virgo/KAGRA S241201ac: Identification of a GW compact binary merger candidate
  39. Konus-Wind detection of GRB 241114B
  40. LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
  41. GRB 241128A: AbAO optical upper limit
  42. LIGO/Virgo/KAGRA S241130be: Identification of a GW compact binary merger candidate
  43. LIGO/Virgo/KAGRA S241130n: Identification of a GW compact binary merger candidate
  44. GRB 241127A: PRIME near-infrared detection
  45. GRB 241128A: Mondy optical observations
  46. GRB 241128A: GRANDMA and Kilonova-Catcher Optical Afterglow Detections and Upperlimits
  47. Swift-XRT observations of IceCube -241127A
  48. LIGO/Virgo/KAGRA S241129aa: Identification of a GW compact binary merger candidate
  49. GRB 241128A: Enhanced Swift-XRT position
  50. GRB 241128A: NOT optical observations
  51. GRB 241128A: LCO optical detection
  52. LIGO/Virgo S241127aj: GRANDMA/FRAM-CTA-N Observations
  53. GRB 241128A: Swift-XRT afterglow detection
  54. GRB 241128A: Swift detection of a burst
  55. GRB 241127A: GRANDMA and Kilonova-Catcher optical afterglow detections
  56. GRB 241127A: Swift/UVOT Detection
  57. GRB 241127A: Enhanced Swift-XRT position
  58. GRB 241127A: LCOGT (40-cm) optical counterpart detection
  59. Swift GRB241127.91: Global MASTER-Net OT detection
  60. EP241126a: WFST Observations
  61. GRB 241127A: Swift detection of a burst with an optical counterpart
  62. Swift GRB241127.91: Global MASTER-Net OT detection
  63. LIGO/Virgo/KAGRA S241125n: Preliminary flux estimate and spectral analysis of the Swift/BAT-GUANO candidate counterpart
  64. LIGO/Virgo/KAGRA S241125n: Swift-UVOT Upper Limits
  65. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations
  66. EP241126a: Optical Upper limits with Kinder observations
  67. IPN triangulation of GRB 241114B
  68. EP trigger ID 01709122294: 1.6m Mephisto multi-band optical observations
  69. EP241126a: GSP detects optical counterpart
  70. EP241126a: TRT optical counterpart detection
  71. LIGO/Virgo/KAGRA S241127aj: Identification of a GW compact binary merger candidate
  72. EP241126a: EP detection of a fast X-ray transient
  73. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on Optical Counterparts to Two of the Swift/XRT Sources
  74. LIGO/Virgo/KAGRA S241125n: SAGUARO follow-up observations with the MMT
  75. LIGO/Virgo/KAGRA S241125n: DDOTI Optical Upper Limits
  76. LIGO/Virgo/KAGRA S241125n: Gaoyazi/GOT optical observations
  77. LIGO/VIRGO/KAGRA S241125n: GROWTH-India telescope optical observations
  78. LIGO/Virgo S241125n: Swift XRT observations, 5 X-ray sources
  79. Konus-Wind detection of GRB 241115D / EP 241115a
  80. LIGO/Virgo/KAGRA S241125n: HCT upper limit
  81. LIGO/Virgo/KAGRA S241125n: Upper limits from Konus-Wind observations
  82. GRB 241026A: radio detection with the VLA
  83. EP241125a: Optical upper limit with Kinder observations
  84. EP241125a: EP detection of an X-ray transient
  85. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on a Optical Counterpart at the BAT Position
  86. LIGO/Virgo/KAGRA S241125n: Kinder optical upper limit in the BAT error region
  87. LIGO/Virgo/KAGRA S241125n: Swift/BAT-GUANO candidate counterpart
  88. GRB 241120A: GRBAlpha detection
  89. LIGO/Virgo/KAGRA S241125n: Identification of a GW compact binary merger candidate
  90. Konus-Wind detection of GRB 241117A
  91. LIGO/Virgo/KAGRA S241122a: Identification of a GW compact binary merger candidate
  92. IPN triangulation of GRB 241117A
  93. GRB 241026A: VIRT Optical Upper Limit
  94. GRB 241025A: VIRT Optical Upper Limit
  95. GRB241120A: OHP/T193 optical observations
  96. EP241021a and EP241026b: Keck/LRIS spectroscopic observations
  97. EP trigger ID 01709065118: Keck/LRIS spectroscopic observations
  98. GRB 241120A: Mondy and AbAO optical observations
  99. EP241119a: Optical upper limits with Kinder observations
  100. EP trigger ID 01709122294: the X-ray transient is likely a stellar flare event

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