diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5c61ab4..aa9c2fc 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -37,6 +37,7 @@ set(TENMON_SRC
     delete.cpp
     filesystemwidget.cpp filesystemwidget.h
     histogram.cpp histogram.h
+    httpdownloader.h httpdownloader.cpp
     imageinfo.cpp imageinfo.h
     imageringlist.cpp imageringlist.h
     imagescrollarea.cpp imagescrollarea.h
@@ -80,7 +81,6 @@ if(COLOR_MANAGMENT)
     target_compile_definitions(tenmon PRIVATE "COLOR_MANAGMENT")
 endif(COLOR_MANAGMENT)
 
-
 target_link_libraries(tenmon PRIVATE Qt6::Widgets Qt6::Sql Qt6::OpenGLWidgets Qt6::Qml ${GSL_LIB} ${GSLCBLAS_LIB} ${EXIF_LIB} ${FITS_LIB} ${RAW_LIB} ${WCS_LIB} ${LCMS2_LIB} XISF)
 if(APPLE)
     target_link_libraries(tenmon PRIVATE Qt6::DBus "-framework CoreFoundation")
diff --git a/httpdownloader.cpp b/httpdownloader.cpp
new file mode 100644
index 0000000..1aa0822
--- /dev/null
+++ b/httpdownloader.cpp
@@ -0,0 +1,494 @@
+#include "httpdownloader.h"
+#include <QNetworkReply>
+#include <QDebug>
+#include <QRegularExpression>
+#include <QStandardPaths>
+#include <QDir>
+
+// filename             arcseconds range
+// index-4119.fits      1400–2000
+// index-4118.fits      1000–1400
+// index-4117.fits      680–1000
+// index-4116.fits      480–680
+// index-4115.fits      340–480
+// index-4114.fits      240–340
+// index-4113.fits      170–240
+// index-4112.fits      120–170
+// index-4111.fits      85–120
+// index-4110.fits      60—85
+// index-4109.fits      42–60
+// index-4108.fits      30–42
+// index-4107.fits      22–30
+// index-5206-*.fits 	16–22
+// index-5205-*.fits 	11–16
+// index-5204-*.fits 	8–11
+// index-5203-*.fits 	5.6–8.0
+// index-5202-*.fits 	4.0–5.6
+// index-5201-*.fits 	2.8–4.0
+
+static const QMap<QString, QByteArray> md5 = {
+    {"index-4107.fits.zst", "b4c3bc2b162fcb6417b2c3358dbf0543"},
+    {"index-4108.fits.zst", "14a54b8e0abcb58efb7a828fc8f00267"},
+    {"index-4109.fits.zst", "d6bce03dfbb527cc807ec360a8b4afa6"},
+    {"index-4110.fits.zst", "da0aded630ee4650850f5828b4289746"},
+    {"index-4111.fits.zst", "c11547481f97727e546b3b7c776f6394"},
+    {"index-4112.fits.zst", "fd3f5ad964d69c66555b2c5b6d65d426"},
+    {"index-4113.fits.zst", "4546e33817a161b8011e5f1321d39445"},
+    {"index-4114.fits.zst", "ebc815fa4d9a3fd259fe22b84796fbc4"},
+    {"index-4115.fits.zst", "5395b7b225ffe5329867354bc653887f"},
+    {"index-4116.fits.zst", "341cebc6b962cede0f27d08c3b3a4f23"},
+    {"index-4117.fits.zst", "e362a868ae0751d1a1e7f6b9e48a2f79"},
+    {"index-4118.fits.zst", "a7d38ec4b1d69c859e875c8d6ba1679b"},
+    {"index-4119.fits.zst", "9e07b46f4c4ca9ba536383d201e70c35"},
+    {"index-5201-00.fits.zst", "87255d073576674ec50959522cbbc9eb"},
+    {"index-5201-01.fits.zst", "b5154f26c8b2a6e143bdc11a062213ab"},
+    {"index-5201-02.fits.zst", "cf0b08e586fe2ce306adb370c9f113e8"},
+    {"index-5201-03.fits.zst", "eda457e3b3b419156b0cbdbe6c262fb7"},
+    {"index-5201-04.fits.zst", "e1344126047714aac771d37861da4698"},
+    {"index-5201-05.fits.zst", "1b2bf2fe61e883db7e65628761a934e8"},
+    {"index-5201-06.fits.zst", "e4338de4ae486cedd31ec24b2677fe1d"},
+    {"index-5201-07.fits.zst", "14665b88b4ab179d1bedd46acdc0d9bd"},
+    {"index-5201-08.fits.zst", "636f411a83dfcf0c02e13ad4c0fed948"},
+    {"index-5201-09.fits.zst", "8afe4edf38794225c1c3b23d72671d96"},
+    {"index-5201-10.fits.zst", "742db3b858e160f69f2d189961fdfcad"},
+    {"index-5201-11.fits.zst", "0ffb50923c71d269acc9c3c661d5429a"},
+    {"index-5201-12.fits.zst", "535eefd763e08593e775e0f4e19c69e3"},
+    {"index-5201-13.fits.zst", "e94426ba2275e76b11495105d780890d"},
+    {"index-5201-14.fits.zst", "754a22f37153773662acaea5ea34a417"},
+    {"index-5201-15.fits.zst", "7e399e94b7a15c2b97e14f49b3999070"},
+    {"index-5201-16.fits.zst", "7441074047de8bccd1c09570b122466d"},
+    {"index-5201-17.fits.zst", "bb7f5979b0d7963420dabfc5dd58407c"},
+    {"index-5201-18.fits.zst", "ca950e0190d849d709357bacce6fc1d0"},
+    {"index-5201-19.fits.zst", "36b84a8ac921064ad1a89f1155af7b31"},
+    {"index-5201-20.fits.zst", "25eeda073f427462e0064acf23a38498"},
+    {"index-5201-21.fits.zst", "0bd79e677363442dc7e994b2f088cd27"},
+    {"index-5201-22.fits.zst", "071abfb9131ca5a6cda792870f97bd8d"},
+    {"index-5201-23.fits.zst", "56721c1918e7ac114d43602ec6b17402"},
+    {"index-5201-24.fits.zst", "4409be2965dacf376b0124d8f7342c3c"},
+    {"index-5201-25.fits.zst", "e784c443787e6c3b3b51e7c82701b3b6"},
+    {"index-5201-26.fits.zst", "02e58904a47e3305dd2a2c1e754c2b56"},
+    {"index-5201-27.fits.zst", "f4f37044f787349dfda36e9aab07c348"},
+    {"index-5201-28.fits.zst", "69893cbd149173c98d496b3d62d23526"},
+    {"index-5201-29.fits.zst", "d55efc9ffca98742f7575c0fa7cd9420"},
+    {"index-5201-30.fits.zst", "014c94da04a6e94897af09001e08bad8"},
+    {"index-5201-31.fits.zst", "376319584d0b6a66bcaced5b31f705d4"},
+    {"index-5201-32.fits.zst", "00f2873b2468d103661e6938fed2d905"},
+    {"index-5201-33.fits.zst", "fa1ce3020ec8511885472c0eda777cd7"},
+    {"index-5201-34.fits.zst", "7c66e555866806d61f90769bc626ef32"},
+    {"index-5201-35.fits.zst", "f1767cf0b802a97b939711f3ecd788c8"},
+    {"index-5201-36.fits.zst", "76825b18fef6546bbbeef3f8538a06cb"},
+    {"index-5201-37.fits.zst", "af507a214fc69c7daa0688fce2924c7e"},
+    {"index-5201-38.fits.zst", "05fc75e562c612c51bf7bacb3907aa02"},
+    {"index-5201-39.fits.zst", "3eeaabf9b945d71fafff7c282f9a3add"},
+    {"index-5201-40.fits.zst", "f891a7def591965ad4aa4ddc9cfb7718"},
+    {"index-5201-41.fits.zst", "48ef1d61841567de4d94d3dc366df643"},
+    {"index-5201-42.fits.zst", "d2c8041bbada7df9dcc5614c35edd7f1"},
+    {"index-5201-43.fits.zst", "24fc923bdc21f696b1da418a131dc2bc"},
+    {"index-5201-44.fits.zst", "690eb483b2d60e1e31ff0e71e1c19167"},
+    {"index-5201-45.fits.zst", "7b7972184b9bd5d485680cb10ad7f566"},
+    {"index-5201-46.fits.zst", "e09515bdd779241b6871eb9130980924"},
+    {"index-5201-47.fits.zst", "95583b10a270336b4cfb31153305b666"},
+    {"index-5202-00.fits.zst", "c877e6a6790d62a77753bc0b5c1c471f"},
+    {"index-5202-01.fits.zst", "2069168ce477a4b9c0659eb97d9d3f3e"},
+    {"index-5202-02.fits.zst", "80b53bdc44addc02c5a9a47183ae405e"},
+    {"index-5202-03.fits.zst", "fcef358afae1ac87e1072bf94c33919f"},
+    {"index-5202-04.fits.zst", "fb6e067de3d8f59868fc5daad9e45ac1"},
+    {"index-5202-05.fits.zst", "168861bd176f0c9283ef091b855cefe8"},
+    {"index-5202-06.fits.zst", "c88d93502450e872004d952f5cc970c6"},
+    {"index-5202-07.fits.zst", "0eb1b5b3b15212f734f150087872a84c"},
+    {"index-5202-08.fits.zst", "03a110b7092787f0da40117d3daf4ee8"},
+    {"index-5202-09.fits.zst", "10b89b70f19e0042c1a832dfbb0f157c"},
+    {"index-5202-10.fits.zst", "6d55a5356f820b437137586037049392"},
+    {"index-5202-11.fits.zst", "ee561de1f6ad229b1aec1d2d576cf2d6"},
+    {"index-5202-12.fits.zst", "16bb2e40a0a71a91b4304c0e030d9f14"},
+    {"index-5202-13.fits.zst", "d6259841cb5209f1fe2262a94ebba80e"},
+    {"index-5202-14.fits.zst", "7fcabd9e89f560dae0ea9032817ffc95"},
+    {"index-5202-15.fits.zst", "42c4006c6482e6a46ed81191d03a6e54"},
+    {"index-5202-16.fits.zst", "a726672e54dd30367664781f533a5f48"},
+    {"index-5202-17.fits.zst", "67fc64ba28344d9fd31143fc5123acb3"},
+    {"index-5202-18.fits.zst", "97ca32bc2a0ab5313547bd01485902e1"},
+    {"index-5202-19.fits.zst", "d261fb13fac3aa19e930d48c6cf13929"},
+    {"index-5202-20.fits.zst", "7a67bc4e1d1dd003280f48815d244b52"},
+    {"index-5202-21.fits.zst", "bbc66dabd84be8fbb47452807aa6cbd5"},
+    {"index-5202-22.fits.zst", "264b65ac94678334ea5dfbc4b329f2ca"},
+    {"index-5202-23.fits.zst", "657492ac072d1679d77abc8f532aa2c9"},
+    {"index-5202-24.fits.zst", "7cbd56e15c84d8b0ad605983aa0eabcb"},
+    {"index-5202-25.fits.zst", "5cd3457ec29821bfca8da6da1ef76684"},
+    {"index-5202-26.fits.zst", "253639c9680bafbbfa465d5de51de235"},
+    {"index-5202-27.fits.zst", "a891918b3c22f7b1e2876358a6e971e2"},
+    {"index-5202-28.fits.zst", "69ee777be98231c104a2e28d2c349111"},
+    {"index-5202-29.fits.zst", "5b9985f33d66e4da27d4c618565f35f4"},
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+    {"index-5202-32.fits.zst", "502ca42a47d5234aab0829a387242dfc"},
+    {"index-5202-33.fits.zst", "253c838df836f569afe854cf598f0c79"},
+    {"index-5202-34.fits.zst", "8dd8e8289e9925058c9cc11e7e76c3e3"},
+    {"index-5202-35.fits.zst", "5b1bb19b81633bb3c2c8d1dff4bb8507"},
+    {"index-5202-36.fits.zst", "7990d2b9a7f120df9095d5a93d3c94f2"},
+    {"index-5202-37.fits.zst", "9e5f0ff891ff1b726df0001547ffd322"},
+    {"index-5202-38.fits.zst", "f06244e6825e4ddb101482295b5294cb"},
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+    {"index-5202-40.fits.zst", "b2d380ef7974fc55f0bf31ebb62ee019"},
+    {"index-5202-41.fits.zst", "ae8058e144898d1b786202345b6581cf"},
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+    {"index-5203-32.fits.zst", "8d09558d167283cf5bff4feca9202421"},
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+    {"index-5206-12.fits.zst", "c132774b1cb656056d04e8175948559f"},
+    {"index-5206-13.fits.zst", "bc491d7a0a773f9e499b9f18f4cc2d26"},
+    {"index-5206-14.fits.zst", "9209a393a7341d08982925936d587178"},
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+    {"index-5206-27.fits.zst", "b63de1ef274c7b3482ec49b038c95e4a"},
+    {"index-5206-28.fits.zst", "0e91227a868e4d626d05f8556fd385db"},
+    {"index-5206-29.fits.zst", "010af2760055eb0b0f139f26808d3d0a"},
+    {"index-5206-30.fits.zst", "bb75c13afb642f8d1039627885591adf"},
+    {"index-5206-31.fits.zst", "9cbec1344ba47dd477d6d8a1f680527e"},
+    {"index-5206-32.fits.zst", "74e832eb93be5e6d58793418253c1b1c"},
+    {"index-5206-33.fits.zst", "303d2fecce3f69914d2aec9b137cd65b"},
+    {"index-5206-34.fits.zst", "b2fa4d6404f11552dd0ae3212a893813"},
+    {"index-5206-35.fits.zst", "18533d28093a1b01ba0a17811237c9c2"},
+    {"index-5206-36.fits.zst", "7f8a6ce0c1e0fe7998a047172bee9390"},
+    {"index-5206-37.fits.zst", "eef8a7d8de31e0865de6a2563cd54602"},
+    {"index-5206-38.fits.zst", "27d0395d69aa600d2c334664ee88191d"},
+    {"index-5206-39.fits.zst", "455e2ee060c16a560e62df0bf6790027"},
+    {"index-5206-40.fits.zst", "9d7f12a0adfb97d7d3b904bf6f8788c4"},
+    {"index-5206-41.fits.zst", "d05556c1d3c15f0cdb72363a82ab6d7c"},
+    {"index-5206-42.fits.zst", "99268fca7e2a9161f4f1c144b13dea3a"},
+    {"index-5206-43.fits.zst", "e3b6becbf0949d9c40dac1d366805493"},
+    {"index-5206-44.fits.zst", "eb6802ea492c8ab920699a47cd8e5ccf"},
+    {"index-5206-45.fits.zst", "d3f692ee8ee9d6c9d3483818f2b81584"},
+    {"index-5206-46.fits.zst", "aff3a7ba7140e5e850c1395fba6402c0"},
+    {"index-5206-47.fits.zst", "27b479b738a7cd3379e105638b1fc43e"}
+};
+
+Download::Download(QNetworkReply *reply, const QString indexPath, QObject *parent) : QObject(parent)
+    ,_reply(reply)
+    ,_hash(QCryptographicHash::Md5)
+{
+    connect(_reply, &QNetworkReply::finished, this, &Download::finished);
+    connect(_reply, &QNetworkReply::readyRead, this, &Download::readData);
+    connect(_reply, &QNetworkReply::downloadProgress, this, &Download::progress);
+
+    QString filename = _reply->url().fileName();
+    filename.remove(QRegularExpression("\\.zst$"));
+
+    _fw.setFileName(indexPath + "/" + filename);
+    _fw.open(QIODevice::WriteOnly | QIODevice::Truncate);
+    if(_fw.isOpen())
+    {
+        qDebug() << "open file" << _fw.fileName();
+    }
+
+    _dstream = ZSTD_createDStream();
+}
+
+Download::~Download()
+{
+    ZSTD_freeDStream(_dstream);
+}
+
+void Download::abort()
+{
+    _reply->abort();
+}
+
+void Download::readData()
+{
+    QByteArray data = _reply->readAll();
+    decompress(data);
+}
+
+void Download::finished()
+{
+    QByteArray data = _reply->readAll();
+    qDebug() << "finished" << data.size();
+    decompress(data);
+
+    if(md5.contains(_reply->url().fileName()))
+    {
+        if(_hash.result().toHex() == md5[_reply->url().fileName()])
+            qDebug() << "DOWNLOAD OK";
+        else
+            qDebug() << "DOWNLOAD BAD";
+    }
+
+    _fw.flush();
+    _fw.close();
+}
+
+void Download::decompress(QByteArray &data)
+{
+    if(data.isEmpty())return;
+
+    _hash.addData(data);
+
+    ZSTD_inBuffer inBuffer = {data.constData(), static_cast<size_t>(data.size()), 0};
+    QByteArray outData(ZSTD_DStreamOutSize(), '\0');
+    while(inBuffer.pos < inBuffer.size)
+    {
+        ZSTD_outBuffer outBuffer = {outData.data(), static_cast<size_t>(outData.size()), 0};
+        size_t ret = ZSTD_decompressStream(_dstream, &outBuffer, &inBuffer);
+        if(ZSTD_isError(ret))
+        {
+            qDebug() << "decompress error" << ZSTD_getErrorName(ret);
+            _fw.remove();
+            _reply->abort();
+            break;
+        }
+        else if(outBuffer.pos)
+        {
+            _fw.write(static_cast<char*>(outBuffer.dst), outBuffer.pos);
+        }
+    }
+}
+
+HttpDownloader::HttpDownloader(QObject *parent) : QObject(parent)
+    ,_manager(new QNetworkAccessManager(this))
+{
+    connect(_manager, &QNetworkAccessManager::finished, this, &HttpDownloader::finished);
+    QDir dir(QStandardPaths::writableLocation(QStandardPaths::AppDataLocation));
+    if(!dir.exists("astrometry"))
+    {
+        if(dir.mkpath("astrometry"))
+            qDebug() << "Failed to create astrometry directory";
+
+    }
+
+    dir.cd("astrometry");
+    _indexPath = dir.absolutePath();
+}
+
+void HttpDownloader::download(const QUrl &url)
+{
+    _queue.enqueue(url);
+    if(!_download)
+        finished();
+}
+
+bool HttpDownloader::downloadIndex(int scale)
+{
+    if(scale > 19 || scale < 1)
+        return false;
+
+    QUrl url("https://nouspiro.space/");
+
+    if(scale >= 7)
+    {
+        url.setPath(QString("/astrometry/index-%1.fits.zst").arg(4100 + scale));
+        download(url);
+    }
+    else
+    {
+        for(int i=0; i<48; i++)
+        {
+            url.setPath(QString("/astrometry/index-%1-%2.fits.zst").arg(5200 + scale).arg(i, 2, 10, QChar('0')));
+            download(url);
+        }
+    }
+    return true;
+}
+
+void HttpDownloader::abort()
+{
+    if(_download)
+        _download->abort();
+}
+
+void HttpDownloader::finished()
+{
+    if(_queue.isEmpty())
+    {
+        _download = nullptr;
+    }
+    else
+    {
+        QUrl url = _queue.dequeue();
+        QString filename = url.fileName();
+        filename.remove(QRegularExpression("\\.zst$"));
+        QFileInfo info(_indexPath + "/" + filename);
+        if(info.exists())
+        {
+            finished();
+            return;
+        }
+        QNetworkRequest request(url);
+        _download->deleteLater();
+        _download = new Download(_manager->get(request), _indexPath, this);
+        connect(_download, &Download::progress, this, &HttpDownloader::updateProgress);
+    }
+}
+
+void HttpDownloader::updateProgress(qint64 received, qint64 total)
+{
+    emit progress((float)received / total * 100.0f, _queue.size());
+}
+
diff --git a/httpdownloader.h b/httpdownloader.h
new file mode 100644
index 0000000..b255943
--- /dev/null
+++ b/httpdownloader.h
@@ -0,0 +1,51 @@
+#ifndef HTTPDOWNLOADER_H
+#define HTTPDOWNLOADER_H
+
+#include <QObject>
+#include <QNetworkAccessManager>
+#include <QFile>
+#include <QQueue>
+#include <QCryptographicHash>
+#include <zstd.h>
+
+class Download : public QObject
+{
+    Q_OBJECT
+    QNetworkReply *_reply;
+    ZSTD_DStream *_dstream;
+    QFile _fw;
+    QCryptographicHash _hash;
+public:
+    Download(QNetworkReply *reply, const QString indexPath, QObject *parent);
+    ~Download();
+    void abort();
+public slots:
+    void readData();
+    void finished();
+signals:
+    void progress(qint64 received, qint64 total);
+protected:
+    void decompress(QByteArray &data);
+};
+
+class HttpDownloader : public QObject
+{
+    Q_OBJECT
+    QNetworkAccessManager *_manager;
+    Download *_download = nullptr;
+    QQueue<QUrl> _queue;
+    QString _indexPath;
+public:
+    explicit HttpDownloader(QObject *parent = nullptr);
+    void download(const QUrl &url);
+    // scale in range 19-1
+    bool downloadIndex(int scale);
+    void abort();
+signals:
+    void progress(int percent, int files);
+protected slots:
+    void finished();
+    void updateProgress(qint64 received, qint64 total);
+};
+
+#endif // HTTPDOWNLOADER_H