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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').
  1. GRB 240715A: Swift/UVOT observations of the XRT sources.
  2. GRB 240715A: Swift-XRT observations
  3. GRB240713A: Swift/UVOT Upper LImits
  4. EP240708a: X-ray follow-up observations with Swift/XRT
  5. GRB 240715A: GECAM-C detection of a short burst
  6. Konus-Wind detection of GRB 240715A
  7. LIGO/Virgo/KAGRA S240716b: Updated Sky localization
  8. GRB 240713A: Swift-XRT observations
  9. GRB 240715A: TRT optical upper limit on one Swift/XRT candidate
  10. GRB 240712A: Swift-XRT refined Analysis
  11. SVOM/GRM In-Flight Trigger of GRB 240715A
  12. GRB 240713A: LAST optical upper limit
  13. LIGO/Virgo/KAGRA S240716b: Identification of a GW compact binary merger candidate
  14. GRB 240715A: Swift ToO observations
  15. Fermi GRB 240715A: Global MASTER-Net observations report
  16. GRB 240713A: optical upper limits from the INAF Asiago Observatory
  17. GRB 240715A: Fermi GBM Observation
  18. GRB 240712A ATCA radio observations
  19. GRB240715A: GRANDMA Optical Upper Limits
  20. IPN triangulation of GRB 240715A (short)
  21. GW s240422ed: Swift UVOT follow-up
  22. GRB 240712A: Swift/UVOT Upper Limits
  23. EP-WXT flaring star and the optical flaring activity during its decay phase
  24. JinShan confirmation of the EP-WXT source triggered on July 14th due to a flaring star
  25. The EP-WXT source triggered on July 14th is likely a flaring star
  26. GRB 240715A: Fermi GBM Final Real-time Localization
  27. GRB 240713A: Tiled Swift observations
  28. GRB 240713A: J-band upper limit from WINTER
  29. GRB 240713A: NOT optical upper limits on three EP/FXT candidates
  30. GRB 240713A: JinShan optical upper limits
  31. GRB 240713A: OHP/T120 optical upper limit
  32. GRB240713A: X-ray follow-up observation with EP-FXT (duplicate submission of GCN 36859)
  33. GRB240713A: X-ray follow-up observation with EP-FXT
  34. GRB 240713B: AstroSat CZTI detection of a long burst
  35. GRB240713A: Optical upper limit with Kinder observations
  36. Fermi Sub-threshold Observation of GRB240713A
  37. GRB240713A: TAROT and GRANDMA Observations of SVOM/ECLAIRs GRB240713A
  38. GRB240713A : The first probable GRB Located on-Board SVOM by ECLAIRs
  39. Fermi Gamma-ray Burst Monitor trigger 742413075/240711744 is not a GRB
  40. EP240708a: GSP optical upper limit
  41. GRB 240712A: Swift detection of a burst
  42. LIGO/Virgo/KAGRA S240711cm: Coverage and upper limits from MAXI/GSC observations
  43. GRB 240711A: Fermi GBM Final Real-time Localization
  44. Fermi trigger No 742405878: Global MASTER-Net observations report
  45. LIGO/Virgo/KAGRA S240627by: Updated Sky localization and EM Bright Classification
  46. Fermi trigger No 742317942: Global MASTER-Net observations report
  47. EP240708a: KAIT optical upper limit
  48. Fermi GRB 240710A: Global MASTER-Net observations report
  49. GRB 240710A: Fermi GBM Final Real-time Localization
  50. EP240708a: NOT optical observations
  51. EP240708a: SVOM/C-GFT optical upper limit
  52. EP240708a: X-ray follow-up observations with EP/FXT and Swift/XRT
  53. EP240708a: Optical upper limits with Kinder observations
  54. EP240708a: EP-WXT detection of a fast X-ray transient
  55. LIGO/Virgo S240615dg: Swift XRT observations, 28 futher X-ray sources
  56. EP240703b: GSP optical upper limit
  57. Fermi Gamma-ray Burst Monitor trigger 741911057/240705933 is not a GRB
  58. GRB 240705A: Fermi GBM Final Real-time Localization
  59. EP240703b: TRT optical upper limits
  60. EP240703a: TRT further optical observation
  61. EP240702a: TRT optical upper limits
  62. Konus-Wind detection of GRB 240627A
  63. IPN triangulation of GRB 240628B (short)
  64. LIGO/Virgo/KAGRA S240705at: Updated Sky localization
  65. EP240703a and EP240703b: Swift/XRT upper limits
  66. LIGO/Virgo/KAGRA S240705at: Identification of a GW compact binary merger candidate
  67. EP240703a: KAIT optical upper limit
  68. EP240703a: BTA observations
  69. EP240703c: Kinder optical follow-up and Swift XRT observations
  70. EP240703a: BOOTES-3 optical upper limit
  71. EP240703a: Liverpool Telescope optical follow-up observations
  72. EP240703a/GRB 240703A: TRT optical candidate likely not real
  73. EP240703a: Kinder optical follow-up observations
  74. EP240703c: EP-WXT detection of an X-ray transient
  75. LIGO/Virgo/KAGRA S240703ad: Updated Sky localization
  76. LIGO/Virgo/KAGRA S240703ad: Identification of a GW compact binary merger candidate
  77. EP240703a/GRB 240703A: TRT and JinShan decaying optical afterglow candidate
  78. IPN triangulation of GRB 240627A
  79. GRB 240619A: Host galaxy redshift from VLT/X-shooter
  80. LIGO/Virgo/KAGRA S240422ed: Updated significance estimate
  81. The first three GRBs detected by SVOM: X-ray Upper Limits from EP-WXT
  82. EP240703b: EP-WXT detection of a fast X-ray transient
  83. Konus-Wind detection of GRB 240703A (a counterpart of EP240703a)
  84. EP240702a: Swift/XRT upper limit
  85. EP240703a: EP-WXT detection of a fast X-ray transient
  86. EP240702a: GSP optical upper limit
  87. The first three GRBs detected by SVOM: GRB 240627B, GRB 240629A and GRB 240702A
  88. GRB 240702A: BALROG localization (Fermi Trigger / GRB 240702885)
  89. Fermi GRB 240702A: Global MASTER-Net observations report
  90. GRB 240702A: Fermi GBM Final Real-time Localization
  91. EP240702a: EP-WXT detection of a fast X-ray transient
  92. LIGO/Virgo/KAGRA S240627by: Upper limits from Swift/BAT-GUANO
  93. Fermi Gamma-ray Burst Monitor trigger 741448122/240630575 is not a GRB
  94. GRB 240627A: CALET Gamma-Ray Burst Monitor detection
  95. Fermi trigger No 741448122: Global MASTER-Net observations report
  96. LIGO/Virgo/KAGRA S240630t: Updated Sky localization
  97. LIGO/Virgo/KAGRA S240629by: Updated Sky localization
  98. LIGO/Virgo/KAGRA S240630t: Identification of a GW compact binary merger candidate
  99. LIGO/Virgo/KAGRA S240629by: Upper limits from Fermi-GBM Observations
  100. LIGO/Virgo/KAGRA S240629by: Coverage and upper limits from MAXI/GSC observations

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