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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').

23834 results found.

  1. EP241126a: Optical Upper limits with Kinder observations
  2. IPN triangulation of GRB 241114B
  3. EP trigger ID 01709122294: 1.6m Mephisto multi-band optical observations
  4. EP241126a: GSP detects optical counterpart
  5. EP241126a: TRT optical counterpart detection
  6. LIGO/Virgo/KAGRA S241127aj: Identification of a GW compact binary merger candidate
  7. EP241126a: EP detection of a fast X-ray transient
  8. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on Optical Counterparts to Two of the Swift/XRT Sources
  9. LIGO/Virgo/KAGRA S241125n: SAGUARO follow-up observations with the MMT
  10. LIGO/Virgo/KAGRA S241125n: DDOTI Optical Upper Limits
  11. LIGO/Virgo/KAGRA S241125n: Gaoyazi/GOT optical observations
  12. GECAM detection of a short burst from SGR 1830
  13. LIGO/VIRGO/KAGRA S241125n: GROWTH-India telescope optical observations
  14. LIGO/Virgo S241125n: Swift XRT observations, 5 X-ray sources
  15. LIGO/Virgo/KAGRA S241125n: HCT upper limit
  16. LIGO/Virgo/KAGRA S241125n: Upper limits from Konus-Wind observations
  17. GRB 241026A: radio detection with the VLA
  18. EP241125a: Optical upper limit with Kinder observations
  19. EP241125a: EP detection of an X-ray transient
  20. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on a Optical Counterpart at the BAT Position
  21. LIGO/Virgo/KAGRA S241125n: Upper limits from Fermi-GBM Observations
  22. LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
  23. LIGO/Virgo/KAGRA S241125n: Kinder optical upper limit in the BAT error region
  24. LIGO/Virgo/KAGRA S241125n: Updated Sky localization
  25. LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
  26. LIGO/Virgo/KAGRA S241125n: No counterpart candidates in INTEGRAL SPI-ACS prompt observation, comparisong with Swift/BAT counterpart
  27. LIGO/Virgo/KAGRA S241109bn: Upper limits from a two-week IceCube neutrino search
  28. LIGO/Virgo/KAGRA S241125n: Updated Sky localization and Coincidence with External Event
  29. LIGO/Virgo/KAGRA S241125n: Swift/BAT-GUANO candidate counterpart
  30. LIGO/Virgo/KAGRA S241125n: Identification of a GW compact binary merger candidate
  31. LIGO/Virgo/KAGRA S241122a: Updated Sky localization and Source Classification
  32. LIGO/Virgo/KAGRA S241122a: Identification of a GW compact binary merger candidate
  33. IPN triangulation of GRB 241117A
  34. GRB 241026A: VIRT Optical Upper Limit
  35. GRB 241025A: VIRT Optical Upper Limit
  36. GRB241120A: OHP/T193 optical observations
  37. EP241021a and EP241026b: Keck/LRIS spectroscopic observations
  38. GRB 241120A: Mondy and AbAO optical observations
  39. EP241119a: Optical upper limits with Kinder observations
  40. EP trigger ID 01709122294: the X-ray transient is likely a stellar flare event
  41. EP241119a: GIT optical upper limits
  42. EP241119a : J-band observations with WINTER
  43. GRB 241120A: Fermi GBM Observation
  44. EP241119a: EP detection of a fast X-ray transient
  45. GRB241120A: a long GRB detected by INTEGRAL
  46. GRB 241112B: Mephisto further optical observations
  47. GRB 241030A: J-band observations
  48. GRB 241115a: PRIME near-infrared upper limits
  49. GRB 241117A: Swift/BAT-GUANO localization skymap of a burst
  50. LIGO/Virgo/KAGRA S241116cq: Upper limits from Swift/BAT-GUANO
  51. GRB 241115B: Fermi GBM Observation
  52. LIGO/Virgo/KAGRA S241114y: Updated Sky localization
  53. Updates to IceCube realtime alert system for muon tracks
  54. GRB 241117A: SVOM/GRM observation of a short burst with extended emission
  55. GRB 241117A: Fermi GBM Detection
  56. IceCube-Cascade 241116A: Upper limits from a search for additional neutrino events in IceCube
  57. LIGO/Virgo/KAGRA S241116cq: Updated Sky localization
  58. GRB 241115B: Swift/BAT-GUANO localization skymap of a long burst
  59. GRB 241115C: Fermi GBM Observation
  60. GRB 241115A: Swift-XRT afterglow detection
  61. LIGO/Virgo/KAGRA S241116cq: Identification of a GW compact binary merger candidate
  62. EP241115a/GRB 241115D: Optical upper limits with Kinder observations
  63. GRB 241115A: Mephisto upper limits
  64. GRB 241113B: Mephisto upper limits
  65. EP241115a/GRB 241115D: Swift/XRT follow-up observation
  66. GRB 241115D / EP 241115a: SVOM/GRM observation
  67. EP241113a: Swift XRT weak detection
  68. GRB 241115A: Fermi GBM Observation
  69. GRB 241115A: LCOGT Optical Upper Limits
  70. GRB 241115C: Swift/BAT-GUANO localization skymap of a burst
  71. LIGO/Virgo/KAGRA S241114bi: Updated Sky localization and EM Bright Classification
  72. LIGO/Virgo/KAGRA S241113p: Updated Sky localization
  73. EP241115a: EP detection of a fast X-ray transient
  74. Swift GRB 241115A: Global MASTER-Net observations report
  75. Fermi GRB 241115A: Global MASTER-Net observations report
  76. GRB 241115A: Swift detection of a burst
  77. EP 241113a: LBT possible optical counterpart
  78. LIGO/Virgo/KAGRA S241114bi: Upper limits from Fermi-GBM Observations
  79. LIGO/Virgo/KAGRA S241114bi: Coverage and upper limits from MAXI/GSC observations
  80. GRB 241113A: Swift-BAT refined analysis
  81. LIGO/Virgo/KAGRA S241114bi: Identification of a GW compact binary merger candidate
  82. GRB 241113A: PRIME near-infrared upper limits
  83. EP241113a: Global MASTER-Net observations report
  84. GRB 241113B: J-band upper limit from WINTER
  85. GRB 241113A: J-band observations with WINTER
  86. EP241113a : J-band observations with WINTER
  87. GRB 241030A: LCO optical observation
  88. GRB 241113B: Swift-XRT observations
  89. IceCube-241113A: Upper limits from a search for additional neutrino events in IceCube
  90. GRB 241113A: 1.6m Mephisto and 50cm array optical upper limits
  91. EP241113b/GRB 241113B: EP detection of GRB 241113B
  92. Fermi-LAT gamma-ray observations of IceCube-241113A
  93. LIGO/Virgo/KAGRA S241114y: Identification of a GW compact binary merger candidate
  94. GRB 241113A: Swift-XRT refined Analysis
  95. GRB 241113A: Swift/UVOT Detection
  96. GRB 241113A: REM detection of the optical/NIR afterglow
  97. LIGO/Virgo/KAGRA S241113p: Identification of a GW compact binary merger candidate
  98. GRB 241113A: LCO optical observations
  99. GRB 241112B: GMG Optical Upper Limit
  100. GRB 241113A: Enhanced Swift-XRT position

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