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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"

31734 results found.

  1. GRB 241018A: Mondy optical upper limit
  2. GRB 241018A: SVOM/VT further analysis and counterpart confirmed
  3. GRB 241018A: GROWTH-India telescope optical upper limit
  4. GRB241018A: XingLong Optical Upper Limit
  5. GRB 241018A: REM optical/NIR upper limits
  6. GRB 241018A: NOT optical observations
  7. GRB 241017A: SVOM/VT follow-up and optical upper limit
  8. GRB 241018A: SVOM/VT follow-up and optical candidate
  9. GRB 241018A: LCO/0.4m optical upper limits
  10. GRB 241018A: Swift ToO observations
  11. GRB 241006A: VIRT Optical Upper Limit
  12. GRB 240727A: VIRT Optical Upper Limit
  13. GRB 241018A: X-ray afterglow candidate observed by MXT
  14. GRB 241016B: Fermi GBM Observations
  15. GRB241017a: Liverpool Telescope observations of XRT uncatalogued sources
  16. GRB 241001A: EP-FXT afterglow detection
  17. GRB 241017A: GROWTH-India Telescope optical upper limit
  18. GRB241017A: TOO Observations by SVOM/MXT
  19. GRB 241016B: Swift/BAT-GUANO localization skymap of a short burst
  20. GRB 241017A: J-band upper limit from WINTER
  21. GRB 241016B: SVOM/GRM observation
  22. GRB 241017A: Swift ToO observations
  23. Fermi GRB 241016B: Global MASTER-Net observations report
  24. Fermi GRB 241016A: Global MASTER-Net observations report
  25. GRB 241010A: Swift-BAT refined analysis
  26. GRB 241013B: Fermi GBM Observation
  27. GRB 241013B: Swift/BAT-GUANO localization skymap of a burst
  28. GRB 241013A: Fermi GBM Observation
  29. GRB 240916A: radio detection with the VLA
  30. GRB241013A: REM observations
  31. GRB 241009A: LCO optical upper limits
  32. GRB 241013B: SVOM/GRM observation
  33. Fermi GRB 241013B: Global MASTER-Net observations report
  34. GRB 241013A: a long GRB detected by INTEGRAL
  35. LIGO/Virgo/KAGRA S241009em: Updated Sky localization
  36. LIGO/Virgo/KAGRA S241011k: Updated Sky localization
  37. LIGO/Virgo/KAGRA S241011k: Identification of a GW compact binary merger candidate
  38. Fermi Gamma-ray Burst Monitor GRB trigger 750372658/241011869 (GRB 241011A) is not a GRB
  39. GRB 241009A: GRANDMA optical upper limits
  40. GRB 241010A: JinShan optical observations and potential host galaxy
  41. GRB 241006A: ATCA Radio Upper Limits
  42. LIGO/Virgo/KAGRA S241007bw: Updated Sky localization
  43. Swift GRB 241010A: Global MASTER-Net observations report
  44. GRB 241010A: J-band observations with WINTER
  45. LIGO/Virgo/KAGRA S241009an: Updated Sky localization
  46. Fermi GRB 241010B: Global MASTER-Net observations report
  47. IceCube-241006A: Upper limits from a search for additional neutrino events in IceCube
  48. GRB 241010A: LCO optical observations
  49. Fermi-LAT Gamma-ray Observations of IceCube-241006A
  50. GRB 241006A: Swift-BAT refined analysis
  51. GRB 241009A: Swift ToO observations
  52. LIGO/Virgo/KAGRA S241009l: Updated Sky localization
  53. LIGO/Virgo/KAGRA S241009em: Identification of a GW compact binary merger candidate
  54. GRB 241008A: Fermi GBM Observation
  55. GRB 241008A: Fermi-LAT detection
  56. GRB 241002B: Swift-XRT afterglow detection
  57. LIGO/Virgo/KAGRA S241009an: Identification of a GW compact binary merger candidate
  58. GRB 241002A: NOT optical upper limits
  59. LIGO/Virgo/KAGRA S241009l: Identification of a GW compact binary merger candidate
  60. Fermi GRB 241008A: Global MASTER-Net observations report
  61. IceCube-241006A: No candidates from the Zwicky Transient Facility
  62. GRB 241006A: GRANDMA optical upper limits
  63. EP240930a / GRB 240930B: CrAO ZTSH optical upper limit
  64. GRB 241002B: PRIME near-infrared detection in 3rd epoch
  65. Fermi-LAT Gamma-ray Observations of NuEm-240926A
  66. GRB 240910A: LBT optical observations
  67. EP trigger ID 01709065118: KAIT confirmation of the stellar flare
  68. GRB 240821A: Host galaxy redshift from VLT/X-shooter
  69. GRB 241006A: PRIME near-infrared upper limits
  70. GRB 241006A: Swift/UVOT Upper Limits
  71. GRB 241006A: SVOM/VT follow-up and optical upper limit
  72. LIGO/Virgo/KAGRA S241007bw: Identification of a GW compact binary merger candidate
  73. GRB 240930B: SVOM/C-GFT optical upper limit
  74. LIGO/Virgo/KAGRA S241006k: Identification of a GW compact binary merger candidate
  75. GRB 240930B / EP 240930a: SVOM/GRM observation
  76. GRB 241001A : ECLAIRs spectral analysis and XRF classification
  77. GRB 241002B: PRIME near-infrared detection in 2nd epoch
  78. GRB 241002B: Fermi GBM Observation
  79. GRB 241002B: Swift-XRT observations
  80. GRB 241002C: SVOM/C-GFT optical upper limit
  81. GRB 241002A: Swift-BAT refined analysis
  82. GRB 241002B: Swift/BAT-GUANO localization skymap of a burst
  83. GRB 241002B: Swift ToO observations
  84. GRB 241002C: Swift-XRT observations confirm the source to be EI Eri
  85. Konus-Wind detection of GRB 240926A
  86. GRB 241002B: PRIME near-infrared detection
  87. GRB 241002C: Swift ToO observations
  88. Fermi-GBM Sub-Threshold Detection of GRB 241002D
  89. IPN triangulation of GRB 240930B / EP 240930a
  90. GRB 241001A : SVOM/VT optical detection
  91. GRB 241002B: GOTO24gpc/AT 2024xbg follow-up observations update
  92. GRB 241002B: ULL-ASTRO-MASTER LCOGT 0.4m + QHY600 detection of the GOTO optical counterpart candidate AT 2024xbg / GOTO24gpc
  93. GRB 240930B: CALET Gamma-Ray Burst Monitor detection
  94. GRB 241002C: X-ray afterglow candidate observed by SVOM/MXT
  95. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  96. GRB 241002C : MITSuME Akeno optical upper limits
  97. LIGO/Virgo/KAGRA S240925n: Updated Sky localization
  98. NuEm-240926A: Upper limits from a search for coincident neutrino events in IceCube
  99. GRB241001A: REM optical/NIR upper limits
  100. LIGO/Virgo/KAGRA S241002e: Updated Sky localization

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